Clearthink 1 Acquisition Corp. (Form: S-1MEF, Received: 02/23/2026 17:30:46)

As filed with the U.S. Securities and Exchange Commission on February 23, 2026

Registration No. 333-

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM S-1

REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933

ClearThink 1 Acquisition Corp.
(Exact name of registrant as specified in its charter)

Cayman Islands		6770		N/A
(State or other jurisdiction of incorporation or organization)		(Primary Standard Industrial Classification Code Number)		(I.R.S. Employer Identification Number)

William Brock
Chief Executive Officer
ClearThink 1 Acquisition Corp.

150 E. Palmetto Park Road

Suite 202
Boca Raton, Florida 33432
Tel: (561) 358-3696
(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Copies to:

Stephen E. Fox

Samantha M. Guido

Ruskin Moscou Faltischek, P.C.

1425 RXR Plaza

East Tower, 15^th Floor

Uniondale, NY 11556

Tel: (516) 663-6600

Cynthia Anandajayasekeram

Bradley Kruger

Ogier (Cayman) LLP

89 Nexus Way, Camana Bay

Grand Cayman, KY1-9009

Cayman Islands

Tel: (345) 949-9876

Darrin Ocasio

Avital Perlman

Sichenzia Ross Ference Carmel LLP

1185 Avenue of the Americas 31^st floor

New York, NY 10036

Tel: (212) 930-9700

Ari Daniel Brown

ClearThink Capital LLC

150 E. Palmetto Park Rd.

Suite 202

Boca Raton, FL 33432

Tel: (561) 807-9010

abrown@clearthink.capital

Approximate date of commencement of proposed sale to the public: As soon as practicable after the effective date of this registration statement.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933 check the following box: ☐

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☒ 333-292967

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Large accelerated filer	☐	Accelerated filer	☐
Non-accelerated filer	☒	Smaller reporting company	☒
		Emerging growth company	☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☐

This registration statement shall become effective upon filing with the Securities and Exchange Commission in accordance with Rule 462(b) under the Securities Act of 1933, as amended.

EXPLANATORY NOTE AND INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

Pursuant to Rule 462(b) under the Securities Act of 1933, as amended (the “Securities Act”), ClearThink 1 Acquisition Corp. (“Registrant”) is filing this Registration Statement on Form S-1 (this “Registration Statement”) with the Securities and Exchange Commission (“Commission”). This Registration Statement relates to the public offering of securities contemplated by the Registration Statement on Form S-1, as amended (File No.: 333-292967) (the “Prior Registration Statement”), which the Registrant originally filed with the Commission on January 26, 2026, and which the Commission declared effective on February 13, 2026.

The Registrant is filing this Registration Statement for the sole purpose of increasing the aggregate number of shares of Class A ordinary shares offered by the Registrant by 1,500,000 shares, or up to 1,750,000 if the underwriters exercise the over-allotment option in full, pursuant to the change of each Unit of the Registrant to consist of one Class A ordinary share and one right to receive one-fifth of one Class A ordinary share upon the consummation of an initial business combination. The additional shares that are being registered for sale are in an amount and at a price that together represent no more than 20% of the maximum aggregate offering price set forth in the Calculation of Registration Fee table contained in the Prior Registration Statement. The information set forth in the Prior Registration Statement and all exhibits to the Prior Registration Statement are incorporated by reference into this Registration Statement.

The required opinions and consents are listed on the Exhibit Index attached hereto and filed herewith. Also filed herewith is an updated form of Rights Agreement between Vstock Transfer Company and the Registrant.

CERTIFICATION

The Registrant hereby certifies to the Commission that (1) it has instructed its bank to pay the filing fee set forth on the Filing Fee Table filed as Exhibit 107 of this Registration Statement by a wire transfer of such amount as soon as practicable (but no later than the close of business on February 23, 2026), (2) it will not revoke such instructions, (3) it has sufficient funds in the relevant account to cover the amount of such filing fee and (4) it will confirm receipt of such instructions by its bank during regular business hours no later than February 23, 2026.

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, the registrant has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Boca Raton, State of Florida, on the 23^rd day of February, 2026.

	CLEARTHINK 1 ACQUISITION CORP.

	By:	/s/ William Brock
	Name:	William Brock
	Title:	Chief Executive Officer and Director

Pursuant to the requirements of the Securities Act of 1933, as amended, this Registration Statement has been signed below by the following persons in the capacities and on the dates indicated.

Name	Position	Date

/s/ WILLIAM BROCK	Chief Executive Officer and Director	February 23, 2026
William Brock	(principal executive officer)

/s/ THOMAS ZIPSER	Chief Financial Officer and Director	February 23, 2026
Thomas Zipser	(principal financial and accounting officer)

/s/ DARWIN HUNT
Darwin Hunt	Director	February 23, 2026

/s/ YOSEF MILGROM
Yosef Milgrom	Director	February 23, 2026

/s/ JULIEN MACHOT
Julien Machot	Director	February 23, 2026

AUTHORIZED U.S. REPRESENTATIVE

Pursuant to the requirements of Section 6(a) of the Securities Act of 1933, as amended, the undersigned, the duly authorized representative in the United States of ClearThink 1 Acquisition Corp., has signed this registration statement in the City of Boca Raton, State of Florida on February 23, 2026.

	By:	/s/ William Brock
	Name:	William Brock
	Title:	Chief Executive Officer

EXHIBIT INDEX

Exhibit Number		Description

4.4		Form of Rights Agreement between VStock Transfer Company and the Registrant

5.1		Opinion of Ruskin Moscou Faltischek, P.C.

5.2		Opinion of Ogier (Cayman) LLP

23.1		Consent of WithumSmith + Brown, P.C.

23.2		Consent of Ruskin Moscou Faltischek, P.C. (included in Exhibit 5.1)

23.3		Consent of Ogier (Cayman) LLP (included in Exhibit 5.2)

107		Filing Fee Table

Exhibit 4.4

RIGHTS AGREEMENT

This Rights Agreement (this “Agreement”) is dated [●], 2026, between ClearThink 1 Acquisition Corp., a Cayman Islands exempted company limited by shares, with principal offices c/o Ogier Global (Cayman) Limited, 89 Nexus Way, Camana Bay, Grand Cayman, KY1-9009, the Cayman Islands (the “Company”) and VStock Transfer LLC, a California limited liability company, with offices at 18 Lafayette Place, Woodmere, NY 11598 (the “Rights Agent”).

RECITALS

WHEREAS, the Company is engaged in an initial public offering (the “Public Offering”) of units of the Company’s equity securities (each, a “Unit” and collectively, the “Units”) through D. Boral Capital LLC, the underwriter (the “Underwriter”) in the Public Offering, each such Unit comprised of one Class A ordinary share of the Company, par value $0.0001 per share (“Ordinary Share”), and one right to receive one-fifth (1/5) of one Ordinary Share (the “Public Rights”) upon the happening of an Exchange Event (as defined below in Section 3.2), and in connection therewith, the Company will issue and deliver up to [17,250,000] Public Rights (including up to [2,250,000] Public Rights subject to the over-allotment option) to public investors in the Public Offering;

WHEREAS, on [●], 2026, the Company entered into those certain Private Units Purchase Agreements with ClearThink 1 Sponsor LLC (the “Sponsor”) and the Underwriter, pursuant to which the Sponsor and the Underwriter agreed to purchase an aggregate of 315,000 private units simultaneously with the closing of the Public Offering at a purchase price of $10.00 per Unit and in connection therewith, will issue and deliver up to an aggregate of 315,000 private units (“Private Placement Rights”);

WHEREAS, in order to finance the Company’s transaction costs in connection with an intended initial Business Combination (as defined in the Company’s amended and restated memorandum and articles of association), the Sponsor or an affiliate of the Sponsor or certain of the Company’s officers and directors may, but are not obligated to, loan to the Company funds as the Company may require, of which up to $1,500,000 may be converted into up to an additional 150,000 private units at a price of $10.00 per Unit, and in connection therewith, the Company will issue and deliver up to an aggregate of 150,000 rights as part of such private units (the “Working Capital Rights”);

WHEREAS, the Company may issue additional rights from time to time that are to be governed by this Agreement (“Post-IPO Rights” and together with the Private Placement Rights, the Working Capital Rights and the Public Rights, the “Rights”) in connection with, or following the consummation by the Company of, a Business Combination;

WHEREAS, the Company has filed with the U.S. Securities and Exchange Commission (the “SEC”) (a) a registration statement on Form S-1, as amended (File No. 333-292967) and (b) a registration statement on Form S-1 (collectively, the “Registration Statement”), and the prospectus forming a part thereof (collectively, the “Prospectus”), for the registration under the Securities Act of 1933, as amended (the “Securities Act”), of the Units, the Public Rights, and the Ordinary Shares issuable to the holders of the Units and the Public Rights and which Registration Statement has been declared effective by the SEC;

WHEREAS, the Company desires the Rights Agent to act on behalf of the Company, and the Rights Agent is willing to so act, in connection with the issuance, registration, transfer and exchange of the Rights;

WHEREAS, the Company desires to provide for the form and provisions of the Rights, the terms upon which they shall be issued, and the respective rights, limitation of rights, and immunities of the Company, the Rights Agent, and the holders of the Rights; and

WHEREAS, all acts and things have been done and performed which are necessary to make the Rights, when executed on behalf of the Company and countersigned by or on behalf of the Rights Agent (if a physical certificate is issued), as provided herein, the valid, binding and legal obligations of the Company, and to authorize the execution and delivery of this Agreement.

NOW, THEREFORE, in consideration of the mutual agreements herein contained, the parties hereto agree as follows:

APPOINTMENT OF RIGHTS AGENT

The Company hereby appoints the Rights Agent to act as agent for the Company for the Rights, and the Rights Agent hereby accepts such appointment and agrees to perform the same in accordance with the terms and conditions set forth in this Agreement.

RIGHTS

2.1 Form of Right

Each Right shall initially be issued in registered form only, and, if a physical certificate is issued, shall be in substantially the form of Exhibit A hereto, the provisions of which are incorporated herein and shall be signed by, or bear the electronic (including by DocuSign) or facsimile signature of, any director or officer of the Company. In the event the person whose electronic or facsimile signature has been placed upon any Right shall have ceased to serve in the capacity in which such person signed the Right before such Right is issued, it may be issued with the same effect as if he or she had not ceased to be such at the date of issuance.

2.2 Effect of Countersignature

Except with respect to uncertificated Rights as described above, unless and until countersigned by the Rights Agent pursuant to this Agreement, a Right shall be invalid and of no effect and may not be exchanged for Ordinary Shares.

2.3 Registration

2.3.1 Right Register

The Rights Agent shall maintain books (“Right Register”) for the registration of original issuance and the registration of transfer of the Rights. Upon the initial issuance of the Rights, the Rights Agent shall issue and register the Rights in the names of the respective holders thereof in such denominations and otherwise in accordance with instructions delivered to the Rights Agent by the Company.

2.3.2 Registered Holder

Prior to due presentment for registration of transfer of any Right, the Company and the Rights Agent may deem and treat the person in whose name such Right shall be registered upon the Right Register (such person, a “Registered Holder”) as the absolute owner of such Right and of each Right represented thereby (notwithstanding any notation of ownership or other writing on the rights certificate made by anyone other than the Company or the Rights Agent), for the purpose of the exchange thereof, and for all other purposes, and neither the Company nor the Rights Agent shall be affected by any notice to the contrary.

2.4 Detachability of Rights

The securities comprising the Units, including the Rights, will begin to trade separately on (i) the first trading day following the 52^nd day after the effectiveness of the Registration Statement, or (ii) such earlier date as the Underwriter shall determine is acceptable. In no event will separate trading of the securities comprising the Units commence until the Company (i) files a Current Report on Form 8-K with the SEC which includes an audited balance sheet reflecting the Company’s receipt of the gross proceeds of the Public Offering and (ii) issues a press release announcing when such separate trading will begin.

TERMS AND EXCHANGE OF RIGHTS

3.1 Rights

Except in cases where the Company is not the surviving entity after the occurrence of an Exchange Event, each holder of a Right shall automatically receive one-fifth (1/5) of one Ordinary Share upon consummation of an Exchange Event. Subject to Section 3.3.4, in the event the Company is not the surviving entity immediately following the Exchange Event, each holder of a Right shall be entitled to automatically receive the kind and amount of securities or properties of the surviving entity as the holders of each one-fifth (1/5) of one Ordinary Share is entitled to receive in such Exchange Event. No additional consideration shall be paid by a holder of Rights in order to receive his, her or its Ordinary Shares upon an Exchange Event, as the purchase price for such Ordinary Shares has been included in the purchase price for the Units. In no event will the Company be required to net cash settle the Rights or issue fractional Ordinary Shares. The provisions of this Section 3.1 may not be modified, amended or deleted without the prior written consent of the Underwriter.

3.2 Exchange Event

An “Exchange Event” shall be deemed to occur automatically upon the Company’s consummation of an initial Business Combination (as defined in the Company’s amended and restated memorandum and articles of association (as may be amended, restated, or amended and restated from time to time (the “Articles”)).

3.3 Exchange of Rights

3.3.1 Issuance of Certificates

As soon as practicable upon the occurrence of an Exchange Event, the Company shall direct holders of the Rights to return their rights certificates (physically or electronically) to the Rights Agent, subject to dissenter rights to the extent provided by applicable law, if any, in the event that the Company is not the surviving entity in a Business Combination. Upon receipt of a valid rights certificate (physically or electronically), the Company shall make (or cause to be made) entries in its Register of Members of the Company and issue to the Registered Holder of such Right(s) a certificate or certificates, or book-entry position, for the number of full Ordinary Shares to which he, she or it is entitled, registered in such name or names as may be directed by him, her or it; provided that in the event that the Company is not the surviving entity following the Exchange Event, the Company shall notify the registered holders of Rights at least two business days prior to the occurrence of the Exchange Event and the registered holders of Rights shall have the right to receive the kind and amount of securities or properties of the surviving entity pursuant to Section 3.3.4 of this Agreement provided that they elect to such conversion, unless such requirement is otherwise waived by the Company. Notwithstanding the foregoing, or any provision contained in this Agreement to the contrary, in no event will the Company be required to net cash settle the Share Rights. The Company shall not issue fractional shares upon exchange of Rights. At the time of an Exchange Event, the Company will instruct the Rights Agent to round down to the nearest whole Ordinary Share.

3.3.2 Valid Issuance

All Ordinary Shares issued upon an Exchange Event in conformity with this Agreement and the Articles, shall, upon registration in the register of members of the Company, be validly issued, fully paid and nonassessable.

3.3.3 Date of Issuance

Each person in whose name any book-entry position or certificate for Ordinary Shares is issued shall for all purposes be deemed to have become the holder of record of such Ordinary Shares on the date that the person’s name is entered in the register of members of the Company, which shall be the date of the Exchange Event, irrespective of the date of delivery of such certificate.

3.3.4 Company Not Surviving Following Exchange Event

Upon an Exchange Event in which the Company does not continue as the surviving entity, each holder of a Right will receive the one-fifth (1/5) of an Ordinary Share underlying each Right (without paying any additional consideration) upon consummation of the Exchange Event. Each holder of a Right will convert the Rights into the underlying Ordinary Shares as well as to return the original certificates (if in certificated form) evidencing the Rights to the Company.

3.4 Duration of Rights

If an Exchange Event does not occur within the time period set forth in the Articles, as the same may be amended from time to time, the Rights shall expire and shall be worthless.

TRANSFER AND EXCHANGE OF RIGHTS

4.1 Registration of Transfer

The Rights Agent shall register the transfer, from time to time, of any outstanding Right upon the Right Register, upon surrender of such Right for transfer, properly endorsed with signatures properly guaranteed and accompanied by appropriate instructions for transfer. Upon any such transfer, a new Right representing an equal aggregate number of Rights shall be issued and the old Right shall be cancelled by the Rights Agent. The Rights so cancelled shall be retained by the Rights Agent for its record.

4.2 Procedure for Surrender of Rights

Rights may be surrendered to the Rights Agent, together with a written request for exchange or transfer, and thereupon the Rights Agent shall issue in exchange therefor one or more new Rights, or book-entry positions, as requested by the Registered Holder of the Rights so surrendered, representing an equal aggregate number of Rights; provided, however, that in the event that a Right surrendered for transfer bears a restrictive legend, the Rights Agent shall not cancel such Right and issue new Rights in exchange therefor until the Rights Agent has received an opinion of counsel for the Company stating that such transfer may be made and indicating whether the new Rights must also bear a restrictive legend.

4.3 Fractional Rights

The Rights Agent shall not be required to effect any registration of transfer or exchange which will result in the issuance of a rights certificate or book-entry position for a fraction of a Right. Fractional shares will either be rounded down to the nearest whole number or otherwise addressed in accordance with Cayman Islands law and the Articles.

4.4 Service Charges

The Company agrees to pay the Rights Agent reasonable remuneration for the registration and transfer of Rights in accordance with a fee schedule to be mutually agreed upon and will reimburse the Rights Agent upon demand for all expenditures that the Rights Agent may reasonably incur in connection therewith.

4.5 Right Execution and Countersignature

The Rights Agent is hereby authorized to countersign and to deliver, in accordance with the terms of this Agreement, the Rights required to be issued pursuant to the provisions of this Section 4, and the Company, whenever required by the Rights Agent, will supply the Rights Agent with Rights duly executed on behalf of the Company for such purpose.

OTHER PROVISIONS RELATING TO RIGHTS OF HOLDERS OF RIGHTS

5.1 No Rights as Shareholder

Until exchange of a Right for Ordinary Shares as provided for herein, a Right does not entitle the Registered Holder thereof to any of the rights of a shareholder of the Company, including, without limitation, the right to receive dividends, or other distributions, exercise any preemptive rights to vote or to consent or to receive notice as shareholders in respect of the general meetings of the Company or the appointment of directors of the Company or any other matter.

5.2 Lost, Stolen, Mutilated, or Destroyed Rights

If any Right is lost, stolen, mutilated, or destroyed, the Company and the Rights Agent may on such terms as to indemnity or otherwise as they may in their discretion impose (which shall, in the case of a mutilated Right, include the surrender thereof), issue a new Right of like denomination, tenor, and date as the Right so lost, stolen, mutilated, or destroyed. Any such new Right shall constitute a substitute contractual obligation of the Company, whether or not the allegedly lost, stolen, mutilated, or destroyed Right shall be at any time enforceable by anyone.

5.3 Reservation of Ordinary Shares

The Company shall at all times reserve and keep available a number of its authorized but unissued Ordinary Shares that will be sufficient to permit the exchange of all outstanding Rights issued pursuant to this Agreement.

5.4 Adjustments to Conversion Ratios

The number of Ordinary Shares that the holders of Rights are entitled to receive as a result of the occurrence of an Exchange Event shall be equitably adjusted to reflect appropriately the effect of any share subdivision, share dividend, reorganization, recapitalization, reclassification, consolidation, exchange of shares or other like change with respect to the Ordinary Shares occurring on or after the date hereof and prior to the Exchange Event.

CONCERNING THE RIGHTS AGENT AND OTHER MATTERS

6.1 Payment of Taxes

The Company will from time to time promptly pay all taxes and charges that may be imposed upon the Company or the Rights Agent in respect of the issuance or delivery of Ordinary Shares upon the exchange of Rights, but the Company shall not be obligated to pay any transfer taxes in respect of the Rights or such Ordinary Shares.

6.2 Resignation, Consolidation, or Merger of Rights Agent

6.2.1 Appointment of Successor Rights Agent

The Rights Agent, or any successor to it hereafter appointed, may resign its duties and be discharged from all further duties and liabilities hereunder after giving sixty (60) days’ notice in writing to the Company. If the office of the Rights Agent becomes vacant by resignation, removal or incapacity to act or otherwise, the Company shall appoint in writing a successor Rights Agent in place of the Rights Agent. If the Company shall fail to make such appointment within a period of 30 days after it has been notified in writing of such resignation, removal or incapacity by the Rights Agent or by the holder of the Right (who shall, with such notice, submit his, her or its Right for inspection by the Company), then the holder of any Right may apply to the Supreme Court of the State of New York for the County of New York for the appointment of a successor Rights Agent at the Company’s cost. Any successor Rights Agent, whether appointed by the Company or by such court, shall be an entity organized and existing under the laws of the United States of America, or any state thereunder, in good standing and authorized under such laws to exercise corporate trust powers and subject to supervision or examination by federal or state authority. After appointment, any successor Rights Agent shall be vested with all the authority, powers, rights, immunities, duties, and obligations of its predecessor Rights Agent with like effect as if originally named as Rights Agent hereunder, without any further act or deed; but if for any reason it becomes necessary or appropriate, the predecessor Rights Agent shall execute and deliver, at the expense of the Company, an instrument transferring to such successor Rights Agent all the authority, powers, and rights of such predecessor Rights Agent hereunder; and upon request of any successor Rights Agent the Company shall make, execute, acknowledge, and deliver any and all instruments in writing for more fully and effectually vesting in and confirming to such successor Rights Agent all such authority, powers, rights, immunities, duties, and obligations.

6.2.2 Notice of Successor Rights Agent

In the event a successor Rights Agent shall be appointed, the Company shall give notice thereof to the predecessor Rights Agent and the transfer agent for the Ordinary Shares not later than the effective date of any such appointment.

6.2.3 Merger or Consolidation of Rights Agent

Any entity into which the Rights Agent may be merged or with which it may be consolidated or any entity resulting from any merger or consolidation to which the Rights Agent shall be a party shall be the successor Rights Agent under this Agreement without any further act.

6.3 Fees and Expenses of Rights Agent

6.3.1 Remuneration

The Company agrees to pay the Rights Agent reasonable remuneration for its services as such Rights Agent hereunder in accordance with a fee schedule to be mutually agreed upon and will reimburse the Rights Agent upon demand for all expenditures that the Rights Agent may reasonably incur in the execution of its duties hereunder.

6.3.2 Further Assurances

The Company agrees to perform, execute, acknowledge, and deliver or cause to be performed, executed, acknowledged, and delivered all such further and other acts, instruments, and assurances as may reasonably be required by the Rights Agent for the carrying out or performing of the provisions of this Agreement.

6.4 Liability of Rights Agent

6.4.1 Reliance on Company Statement

Whenever in the performance of its duties under this Agreement, the Rights Agent shall deem it necessary or desirable that any fact or matter be proved or established by the Company prior to taking or suffering any action hereunder, such fact or matter (unless other evidence in respect thereof be herein specifically prescribed) may be deemed to be conclusively proved and established by a statement signed by a director or officer of the Company and delivered to the Rights Agent. The Rights Agent may rely upon such statement for any action taken or suffered in good faith by it pursuant to the provisions of this Agreement.

6.4.2 Indemnity

The Rights Agent shall be liable hereunder only for its own gross negligence, willful misconduct or bad faith, or material breach of this Agreement (each as determined by a final, non-appealable judgment of a court of competent jurisdiction). Subject to Section 6.6 below, the Company agrees to indemnify the Rights Agent and save it harmless against any and all liabilities, including judgments, costs and reasonable counsel fees, for anything done or omitted by the Rights Agent in the execution of this Agreement, except as a result of the Rights Agent’s gross negligence, willful misconduct or bad faith, or material breach of this Agreement (each as determined by a final, non-appealable judgment of a court of competent jurisdiction).

6.4.3 Exclusions

The Rights Agent shall have no responsibility with respect to the validity of this Agreement or with respect to the validity or execution of any Right (except its countersignature thereof); nor shall it be responsible for any breach by the Company of any covenant or condition contained in this Agreement or in any Right; nor shall it by any act hereunder be deemed to make any representation or warranty as to the authorization or reservation of any Ordinary Shares to be issued pursuant to this Agreement or any Right or as to whether any Ordinary Shares will when issued be valid and fully paid and nonassessable.

6.5 Acceptance of Agency

The Rights Agent hereby accepts the agency established by this Agreement and agrees to perform the same upon the terms and conditions herein set forth.

6.6 Waiver

The Rights Agent hereby waives any right of set-off or any other right, title, interest or claim of any kind (“Claim”) in, or to any distribution of, the Trust Account (as defined in that certain Investment Management Trust Agreement, dated as of the date hereof, by and between the Company and the Rights Agent as trustee thereunder) and hereby agrees not to seek recourse, reimbursement, payment or satisfaction for any Claim against the Trust Account for any reason whatsoever.

MISCELLANEOUS PROVISIONS

7.1 Successors

All the covenants and provisions of this Agreement by or for the benefit of the Company or the Rights Agent shall bind and inure to the benefit of their respective successors and assigns.

7.2 Notices

Any notice, statement or demand authorized by this Agreement to be given or made by the Rights Agent or by the holder of any Right to or on the Company shall be sufficiently given when so delivered if by hand or overnight delivery or if sent by certified mail or private courier service within five days after deposit of such notice, postage prepaid, addressed (until another address is filed in writing by the Company with the Rights Agent), as follows:

ClearThink 1 Acquisition Corp.

150 E. Palmetto Park Road

Suite 202

Boca Raton, Florida 33432

Attention: Chief Executive Officer

Any notice, statement or demand authorized by this Agreement to be given or made by the holder of any Right or by the Company to or on the Rights Agent shall be sufficiently given when so delivered if by hand or overnight delivery or if sent by certified mail or private courier service within five days after deposit of such notice, postage prepaid, addressed (until another address is filed in writing by the Rights Agent with the Company), as follows:

VStock Transfer LLC

18 Lafayette Place

Woodmere, NY 11598

Attention: Compliance

7.3 Applicable Law

The validity, interpretation, and performance of this Agreement and of the Rights shall be governed in all respects by the laws of the State of New York, without giving effect to conflicts of law principles that would result in the application of the substantive laws of another jurisdiction. The Company hereby agrees that any action, proceeding or claim against it arising out of or relating in any way to this Agreement shall be brought and enforced in the courts of the State of New York or the United States District Court for the Southern District of New York, and irrevocably submits to such jurisdiction, which jurisdiction shall be exclusive. The Company hereby waives any objection to such exclusive jurisdiction and that such courts represent an inconvenient forum. Notwithstanding the foregoing, this exclusive forum provision shall not apply to suits brought to enforce any liability or duty created by the Securities Act or the Securities Exchange Act of 1934, as amended (“Exchange Act”), any other claim for which the federal district courts of the United States of America are the sole and exclusive forum. Any process or summons to be served upon the Company may be served by transmitting a copy thereof by registered or certified mail, return receipt requested, postage prepaid, addressed to it at the address set forth in Section 7.2 hereof. Such mailing shall be deemed personal service and shall be legal and binding upon the Company in any action, proceeding or claim.

7.4 Persons Having Rights under this Agreement

Nothing in this Agreement expressed and nothing that may be implied from any of the provisions hereof is intended, or shall be construed, to confer upon, or give to, any person or corporation other than the parties hereto and the Registered Holders of the Rights and, for the purposes of Sections 3.1, 7.4 and 7.8 hereof, the Underwriter, any right, remedy, or claim under or by reason of this Agreement or of any covenant, condition, stipulation, promise, or agreement hereof. The Underwriter shall be deemed to be a third-party beneficiary of this Agreement with respect to Sections 3.1, 7.4 and 7.8 hereof. All covenants, conditions, stipulations, promises, and agreements contained in this Agreement shall be for the sole and exclusive benefit of the parties hereto (and the Underwriter with respect to the Sections 3.1, 7.4 and 7.8 hereof) and their successors and assigns and of the Registered Holders of the Rights. The provisions of this Section 7.4 may not be modified, amended or deleted without the prior written consent of the Underwriter.

7.5 Examination of the Rights Agreement

A copy of this Agreement shall be available at all reasonable times at the office of the Rights Agent in the City of New York and State of New York, for inspection by the Registered Holder of any Right. The Rights Agent may require any such holder to submit his, her or its Right for inspection by it.

7.6 Counterparts

This Agreement may be executed in any number of original, electronic or facsimile counterparts and each of such counterparts shall for all purposes be deemed to be an original, and all such counterparts shall together constitute but one and the same instrument. A signature to this Agreement transmitted electronically shall have the same authority, effect, and enforceability as an original signature.

7.7 Effect of Headings

The Section headings herein are for convenience only and are not part of this Agreement and shall not affect the interpretation thereof.

7.8 Amendments

This Agreement may be amended by the parties hereto without the consent of any Registered Holder for the purpose of curing any ambiguity, or of curing, correcting or supplementing any defective provision contained herein or adding or changing any other provisions with respect to matters or questions arising under this Agreement as the parties may deem necessary or desirable and that the parties deem shall not adversely affect the interest of the Registered Holders. All other modifications or amendments shall require the written consent or vote of the Registered Holders of a majority of the then outstanding Rights. The provisions of this Section 7.8 may not be modified, amended or deleted without the prior written consent of the Underwriter.

7.9 Severability

This Agreement shall be deemed severable, and the invalidity or unenforceability of any term or provision hereof shall not affect the validity or enforceability of this Agreement or of any other term or provision hereof. Furthermore, in lieu of any such invalid or unenforceable term or provision, the parties hereto intend that there shall be added as a part of this Agreement a provision as similar in terms to such invalid or unenforceable provision as may be possible and be valid and enforceable.

[SIGNATURE PAGE FOLLOWS]

SIGNATURE PAGE

IN WITNESS WHEREOF, this Agreement has been duly executed by the parties hereto as of the day and year first above written

	ClearThink 1 Acquisition Corp.

	By:
	Name:
	Title:

	VStock Transfer LLC

	By:
	Name:
	Title:

EXHIBIT A

Form of Rights Certificate

NUMBER

SEE REVERSE FOR

CERTAIN DEFINITIONS

CLEARTHINK 1 ACQUISITION CORP.

CUSIP

INCORPORATED UNDER THE LAWS OF THE CAYMAN ISLANDS

RIGHT

THIS CERTIFIES THAT, for value received________________________________________

is the registered holder of a right or rights (each, a “Right”) to automatically receive one-fifth (1/5) of one Class A ordinary share, $0.0001 par value (“Ordinary Shares”), of ClearThink 1 Acquisition Corp., a Cayman Islands exempted company (the “Company”) for each Right evidenced by this Right Certificate on the Company’s completion of an initial business combination (as defined in the prospectus relating to the Company’s initial public offering (“Prospectus”)) upon surrender of this Right Certificate pursuant to the Rights Agreement between the Company and VStock Transfer, as Rights Agent. In no event will the Company be required to net cash settle any Right or issue a fractional Ordinary Share.

Upon liquidation of the Company in the event an initial business combination is not consummated during the required period as identified in the Company’s memorandum and articles of association, as may be further amended from time to time (“Memorandum and Articles”), the Right shall expire and be worthless. The holder of a Right shall have no right or interest of any kind in the Company’s trust account (as defined in the Prospectus).

Upon due presentment for registration of transfer of the Right Certificate at the office or agency of the Rights Agent, a new Right Certificate or Right Certificates of like tenor and evidencing in the aggregate a like number of Rights shall be issued to the transferee in exchange for this Right Certificate, without charge except for any applicable tax or other governmental charge. The Company shall not issue fractional shares upon exchange of Rights. The Company reserves the right to deal with any fractional entitlement at the relevant time in any manner (as provided in the Rights Agreement).

The Company and the Rights Agent may deem and treat the registered holder as the absolute owner of this Right Certificate (notwithstanding any notation of ownership or other writing hereon made by anyone), for the purpose of any conversion hereof, of any distribution to the registered holder, and for all other purposes, and neither the Company nor the Right Agent shall be affected by any notice to the contrary.

This Right does not entitle the registered holder to any of the rights of a shareholder of the Company. This Right shall be governed by and construed in accordance with the internal laws of the State of New York, without regard to conflicts of laws principles thereof.

Dated:

VStock Transfer

ClearThink 1 Acquisition Corp.

The following abbreviations, when used in the inscription on the face of this certificate, shall be construed as though they were written out in full according to applicable laws or regulations:

TEN COM — as tenants in common

TEN ENT — as tenants by the entireties

JT TEN — as joint tenants with right of survivorship and not as tenants in common

UNIF GIFT MIN ACT —	______________ Custodian _______________
	(Cust) (Minor)

	under Uniform Gifts to Minors Act


	(State)

Additional Abbreviations may also be used though not in the above list.

The Company will furnish without charge to each shareholder who so requests, a statement of the powers, designations, preferences and relative, participating, optional or other special rights of each class of shares or series thereof of the Company and the qualifications, limitations, or restrictions of such preferences and/or rights. This certificate and the rights represented thereby are issued and shall be held subject to all the provisions of the Memorandum and Articles and resolutions of the Board of Directors providing for the issue of Ordinary Shares (copies of which may be obtained from the secretary of the Company), to all of which the holder of this certificate by acceptance hereof assents.

For value received, ___________________________ hereby sell(s), assign(s) and transfer(s) unto

PLEASE INSERT SOCIAL SECURITY OR OTHER
IDENTIFYING NUMBER OF ASSIGNEE(S)

(PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE(S))

Rights represented by the within Certificate, and do hereby irrevocably constitute and appoint

Attorney to transfer the said Units on the books of the within named Company will full power of substitution in the premises.

Dated


	Notice:	The signature to this assignment must correspond with the name as written upon the face of the certificate in every particular, without alteration or enlargement or any change whatever.

Signature(s) Guaranteed:

THE SIGNATURE(S) SHOULD BE GUARANTEED BY AN ELIGIBLE GUARANTOR INSTITUTION (BANKS, STOCKBROKERS, SAVINGS AND LOAN ASSOCIATIONS AND CREDIT UNIONS WITH MEMBERSHIP IN AN APPROVED SIGNATURE GUARANTEE MEDALLION PROGRAM, PURSUANT TO S.E.C. RULE 17Ad-15).

The holder of this certificate shall have no right or interest of any kind in or to the funds held in the Company’s trust account (as defined in the Prospectus).

Exhibit 5.1

February 23, 2026

ClearThink 1 Acquisition Corp.

150 E. Palmetto Park Road

Suite 202

Boca Raton, Florida 33432

Re:

Registration Statement on Form S-1

Ladies and Gentlemen:

We have acted as counsel to ClearThink 1 Acquisition Corp. (the “Company”) in connection with the preparation and filing of that certain (a) Registration Statement on Form S-1, as amended (the “Prior Registration Statement”), originally filed on January 26, 2026 with the Securities and Exchange Commission (the “SEC”), and (b) Registration Statement on Form S-1 (the “462(b) Registration Statement” and, with the Prior Registration Statement, the “Registration Statements”), in each case under the Securities Act of 1933, as amended, with respect to an underwritten public offering of (i) 15,000,000 units (the “Units”), with each Unit consisting of one of the Company’s Class A ordinary shares, par value $0.0001 per share (the “Ordinary Shares”) and one right to receive one-fifth of an Ordinary Share (the “Rights”); (ii) up to 2,250,000 Units (the “Over-Allotment Units”) for which the underwriter has been granted an over-allotment option, (iii) all Ordinary Shares and Rights issued as part of the Units and Over-Allotment Units; and (iv) all Ordinary Shares issuable upon conversion of the Rights included in the Units and Over-Allotment Units. The Units and the Over-Allotment Units are referred to herein as the “Registered Securities.” We understand that the Units and Over-Allotment Units are proposed to be sold for sale to the public as described in the Registration Statements and pursuant to an underwriting agreement, substantially in the form filed as an exhibit to the Prior Registration Statement, to be entered into by the Company and the underwriter (the “Underwriting Agreement”).

As counsel to the Company, we have examined the originals or copies of such documents, corporate records and other instruments and undertaken such further inquiry as we have deemed necessary or appropriate for purposes of this opinion, including, but not limited to, the Registration Statement, corporate resolutions authorizing the issuance of the Units and Over-Allotment Units and the Amended and Restated Memorandum and Articles of Association of the Company, including amendments thereto. In such examination, we have assumed the following: (a) the authenticity of original documents and the genuineness of all signatures; (b) the legal capacity of all natural persons, the accuracy and completeness of all documents submitted to us; (c) the conformity to the originals of all documents submitted to us as copies; (d) the genuineness of all signatures contained in the records, documents, instruments and certificates we have reviewed; and (e) the truth, accuracy and completeness of the information, representations and warranties contained in the records, documents, instruments and certificates we have reviewed. This opinion letter is given, and all statements herein are made, in the context of the foregoing.

Based upon the foregoing and subject to the assumptions, exceptions, qualifications and limitations set forth hereinafter, we are of the opinion that each of the Rights (including the Rights issuable in connection with the Over-Allotment Units), the Units and the Over-Allotment Units, if and when paid for in accordance with the terms of the Underwriting Agreement will constitute the valid and legally binding obligation of the Company, enforceable against it in accordance with its terms.

February 23, 2026

Page 2

The opinion set forth above, is subject to (i) the effect of any applicable bankruptcy, insolvency, reorganization, moratorium or similar law relating to or affecting creditors’ rights generally (including, without limitation, fraudulent conveyance laws) and (ii) the effect of general principles of equity, including, without limitation, concepts of materiality, reasonableness, good faith and fair dealing and the possible unavailability of specific performance or injunctive relief, regardless whether considered in a proceeding in equity or at law. We express no opinion as to the enforceability of (i) provisions that relate to choice of law, forum selection or submission to jurisdiction (including, without limitation, any express or implied waiver of any objection to venue in any court or of any objection that a court is an inconvenient forum) to the extent that the validity, binding effect or enforceability of any such provision is to be determined by any court other than a state court of the State of New York or (ii) waivers by the Company of any statutory or constitutional rights or remedies. We draw your attention to the fact that, under certain circumstances, the enforceability of terms to the effect that provisions may not be waived or modified except in writing may be limited.

In rendering the foregoing opinion, we have assumed that: (i) the Registration Statement, and any amendments thereto, shall have become effective under the Securities Act and will remain effective at the time of issuance of the Registered Securities thereunder; (ii) the Company will issue and deliver the Registered Securities in the manner contemplated by the final prospectus; and (iii) all such securities will be issued in compliance with applicable federal and state securities laws. To the extent the obligations of the Company with respect to the Registered Securities may be dependent upon such matters, we also assume for purposes of this letter that the other party under the Underwriting Agreement, is duly authorized validly existing and in good standing under the laws of its jurisdiction of organization; that such party is duly qualified to engage in the activities contemplated by the Underwriting Agreement; that such Underwriting Agreement has been duly authorized, executed and delivered by the other party and constitutes the valid and binding obligation of the other party enforceable against the other party in accordance with its terms; that such other party is in compliance with respect to performance of its obligations under such Underwriting Agreement with all applicable laws and regulations; and such other party has the requisite organizational and legal power and authority to perform its obligations under the Underwriting Agreement.

The information set forth herein is as of the date hereof. We assume no obligation to advise you of changes that may hereafter be brought to our attention. Without limiting the generality of the foregoing, we neither express nor imply any opinion regarding (a) the contents of the Registration Statements or the related prospectus, or (b) the Ordinary Shares that make up a portion of the Registered Securities or that underly the Rights, in either case other than as expressly stated herein with respect to the Registered Securities to be issued pursuant to the Registration Statement. We are members of the Bar of the State of New York. We do not express any opinion concerning the laws of any jurisdiction other than (i) the State of New York and (ii) the Federal laws of the United States. Our opinion is based on statutory laws and judicial decisions that are in effect on the date hereof, and we do not opine with respect to any law, regulation, rule or governmental policy that may be enacted or adopted after the date hereof, nor do we assume any responsibility to advise you of future changes in our opinion. We do not express an opinion on any matters other than those expressly set forth in this letter.

No opinion is expressed herein with respect to the qualification of the Registered Securities under the securities or blue sky laws of any state or any foreign jurisdiction. In particular, we do not purport to pass on any matter governed by the laws of the Cayman Islands.

We hereby consent to the use and filing of this opinion as an exhibit to the 462(b) Registration Statement as filed with the Securities and Exchange Commission and to the reference to our firm under the heading “Legal Matters” in the Prospectus and the Registration Statement. In giving this consent, we do not admit that we are within the category of persons whose consent is required under Section 7 of the Act or the rules and regulations of the Securities and Exchange Commission promulgated thereunder.

	Very truly yours,

	/s/ Ruskin Moscou Faltischek PC

	RUSKIN MOSCOU FALTISCHEK, P.C.

Exhibit 5.2

ClearThink 1 Acquisition Corp.		D +1 345 815 1877
89 Nexus Way		E bradley.kruger@ogier.com
Camana Bay
Grand Cayman		Reference: 514810.00001
Cayman Islands
KY1-9009
		23 February 2026

ClearThink 1 Acquisition Corp. (the Company)

We have been requested to provide you with an opinion on matters of Cayman Islands law in connection with the Company’s registration statement on Form S-1, including all amendments or supplements thereto, filed with the United States Securities and Exchange Commission (the Commission) under the United States Securities Act of 1933 (the Act), as amended, (including its exhibits, the Registration Statement) related to the offering and sale of:

(a)	up to 15,000,000 units (the Units), each Unit consisting of one class A ordinary share of the Company of par value of US$0.0001 each (the Class A Ordinary Shares) and one right to receive one-fifth (1/5) of one Class A Ordinary Share (the Rights);

(b)	up to 2,250,000 Units (the Over-Allotment Units) which several underwriters, for whom D. Boral Capital LLC is acting as representative, will have a right to purchase from the Company to cover over-allotments, if any;

(c)	315,000 Units will be issued to ClearThink 1 Sponsor LLC (the Sponsor) in a private placement that will close simultaneously with the closing of the offering (the Private Placement Units)

(d)	all Class A Ordinary Shares and all Rights issued as part of the Units, the Over-Allotment Units, and the Private Placement Units; and

(e)	all Class A Ordinary Shares that may be issued upon conversion of the Rights included in the Units, the Over-Allotment Units, and the Private Placement Units.

Ogier (Cayman) LLP

89 Nexus Way

Camana Bay

Grand Cayman, KY1-9009

Cayman Islands

T +1 345 949 9876

F +1 305 513 5888

ogier.com

A list of Partners may be inspected on our website

ClearThink 1 Acquisition Corp.

23 February 2026

This opinion is given in accordance with the terms of the Legal Matters section of the Registration Statement.

Unless a contrary intention appears, all capitalised terms used in this opinion have the respective meanings set forth in Schedule 1. A reference to a Schedule is a reference to a schedule to this opinion and the headings herein are for convenience only and do not affect the construction of this opinion.

1	Documents examined

For the purposes of giving this opinion, we have examined the corporate and other documents and conducted the searches listed in Schedule 1. We have not made any searches or enquiries concerning, and have not examined any documents entered into by or affecting the Company or any other person, save for the searches, enquiries and examinations expressly referred to in Schedule 1.

2	Assumptions

In giving this opinion we have relied upon the assumptions set forth in Schedule 2 without having carried out any independent investigation or verification in respect of those assumptions.

3	Opinions

On the basis of the examinations and assumptions referred to above and subject to the qualifications set forth in Schedule 3 and the limitations set forth below, we are of the opinion that:

Corporate status

(a)

The Company has been duly incorporated as an exempted company with limited liability and is validly existing and in good standing with the Registrar of Companies of the Cayman Islands (the Registrar).

Corporate power

(b)

The Company has under the A&R M&A, all requisite power to issue the Class A Ordinary Shares (including the issuance of the Class A Ordinary Shares upon the conversion of the Rights in accordance with the Rights Documents), to execute and deliver the Documents and to perform its obligations, and exercise its rights, under such documents.

ClearThink 1 Acquisition Corp.

23 February 2026

Corporate authorisation

(c)

The Company has taken all requisite corporate action to authorise:

	(i)	the issuance of the Class A Ordinary Shares (including the issuance of the Class A Ordinary Shares upon the conversion of the Rights in accordance with the Rights Documents); and

	(ii)	the execution and delivery of the Documents and the performance of its obligations, and the exercise of its rights, under such documents.

Shares

(d)

The Class A Ordinary Shares to be offered and issued by the Company as contemplated by the Registration Statement (including the issuance of the Class A Ordinary Shares upon the conversion of the Rights in accordance with the Rights Documents), when issued by the Company upon:

	(i)	payment in full of the consideration as set out in the Registration Statement and in accordance with the terms set out in the Registration Statement (including the issuance of the Class A Ordinary Shares upon the conversion of the Rights in accordance with the Rights Documents) and in accordance with the A&R M&A; and

	(ii)	the entry of those Class A Ordinary Shares as fully paid on the register of members of the Company,

shall be validly issued, fully paid and non-assessable.

4	Matters not covered

We offer no opinion:

	(a)	as to any laws other than the laws of the Cayman Islands, and we have not, for the purposes of this opinion, made any investigation of the laws of any other jurisdiction, and we express no opinion as to the meaning, validity, or effect of references in the Documents to statutes, rules, regulations, codes or judicial authority of any jurisdiction other than the Cayman Islands;

	(b)	except to the extent that this opinion expressly provides otherwise, as to the commercial terms of, or the validity, enforceability or effect of the documents reviewed (or as to how the commercial terms of such documents reflect the intentions of the parties), the accuracy of representations, the fulfilment of warranties or conditions, the occurrence of events of default or terminating events or the existence of any conflicts or inconsistencies among the documents and any other agreements into which the Company may have entered or any other documents; or

	(c)	as to whether the acceptance, execution or performance of the Company’s obligations under the documents reviewed by us will result in the breach of or infringe any other agreement, deed or document (other than, to the extent expressly provided herein, the A&R M&A) entered into by or binding on the Company.

ClearThink 1 Acquisition Corp.

23 February 2026

5	Governing law of this opinion

5.1

This opinion is:

	(a)	governed by, and shall be construed in accordance with, the laws of the Cayman Islands;

	(b)	limited to the matters expressly stated in it; and

	(c)	confined to, and given on the basis of, the laws and practice in the Cayman Islands at the date of this opinion.

5.2

Unless otherwise indicated, a reference to any specific Cayman Islands legislation is a reference to that legislation as amended to, and as in force at, the date of this opinion.

6	Consent

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and also consent to the reference to this firm in the Registration Statement under the heading “Legal Matters”. In the giving of our consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Act or the Rules and Regulations of the Commission thereunder.

Yours faithfully

/s/ Ogier (Cayman) LLP
Ogier (Cayman) LLP

ClearThink 1 Acquisition Corp.

23 February 2026

Schedule 1

Documents examined and searches conducted

1	The certificate of incorporation of the Company dated 11 September 2025 issued by the Registrar (the Certificate of Incorporation).

2	The amended and restated memorandum and articles of association adopted by special resolution dated 13 February 2026 (the A&R M&A).

3	A certificate of good standing dated 20 February 2026 issued by the Registrar in respect of the Company (the Good Standing Certificate).

4	A certificate dated on the date hereof as to certain matters of fact signed by a director of the Company in the form annexed hereto (the Director’s Certificate), having attached to it copies of the written resolutions of the directors of the Company passed on 16 October 2025, 22 October 2025, and 10 February 2026 (the Resolutions).

5	The Register of Writs maintained by the office of the Clerk of Courts in the Cayman Islands as inspected by us on 23 February 2026 (the Register of Writs).

6	The Registration Statement.

7	A draft of the form of the unit certificate representing the Units, the Over-Allotment Units, and the Private Placement Units (the Unit Certificates).

8	A draft specimen certificate for Class A Ordinary Shares (the Share Certificates).

9	A draft of the form of the rights agreement and the rights certificate constituting the Rights (the Rights Documents and, together with the Unit Certificates and the Share Certificates, the Documents).

ClearThink 1 Acquisition Corp.

23 February 2026

Schedule 2

Assumptions

Assumptions of general application

1	All original documents examined by us are authentic and complete.

2	All copy documents examined by us (whether in facsimile, electronic or other form) conform to the originals and those originals are authentic and complete.

3	All signatures, seals, dates, stamps and markings (whether on original or copy documents) are genuine.

4	Each of the Good Standing Certificate and the Director’s Certificate is accurate and complete as at the date of this opinion.

5	Where any Document has been provided to us in draft or undated form, that Document has been, or will be, executed by all parties in materially the form provided to us and, where we have been provided with successive drafts of a Document marked to show changes from a previous draft, all such changes have been accurately marked.

Status, authorisation and execution

6	Each of the parties to the Documents other than the Company is duly incorporated, formed or organised (as applicable), validly existing and in good standing under all relevant laws.

7	Each Document has been duly authorised, executed and unconditionally delivered by or on behalf of all parties to it (other than the Company) in accordance with all applicable laws.

8	In authorising the execution and delivery of the Documents by the Company, the issue and allotment of the Class A Ordinary Shares and Rights, and the exercise of its rights and performance of its obligations under the Documents, each of the directors of the Company has acted in good faith with a view to the best interests of the Company and has exercised the standard of care, diligence and skill that is required of him or her.

ClearThink 1 Acquisition Corp.

23 February 2026

Enforceability

9	None of the opinions expressed herein will be adversely affected by the laws or public policies of any jurisdiction other than the Cayman Islands. In particular, but without limitation to the previous sentence:

	(a)	the laws or public policies of any jurisdiction other than the Cayman Islands will not adversely affect the capacity or authority of the Company; and

	(b)	neither the execution or delivery of the Documents nor the exercise by any party to the Documents of its rights or the performance of its obligations under them contravene those laws or public policies.

Share Issuance

10	The Class A Ordinary Shares to be issued shall be issued at an issue price in excess of the par value thereof.

Register of Writs

11	The Register of Writs constitutes a complete and accurate record of the proceedings affecting the Company before the Grand Court of the Cayman Islands as at the time we conducted our investigation of such register.

ClearThink 1 Acquisition Corp.

23 February 2026

Schedule 3

Qualifications

Good Standing

Under the Companies Act (Revised) of the Cayman Islands (Companies Act) annual returns in respect of the Company must be filed with the Registrar, together with payment of annual filing fees. A failure to file annual returns and pay annual filing fees may result in the Company being struck off the Register of Companies, following which its assets will vest in the Financial Secretary of the Cayman Islands and will be subject to disposition or retention for the benefit of the public of the Cayman Islands.

In good standing means only that as of the date of the Good Standing Certificate the Company is up-to-date with the filing of its annual returns and payment of annual fees with the Registrar. We have made no enquiries into the Company’s good standing with respect to any filings or payment of fees, or both, that it may be required to make under the laws of the Cayman Islands other than the Companies Act.

Limited Liability

We are not aware of any Cayman Islands authority as to when the courts would set aside the limited liability of a shareholder in a Cayman Islands company. Our opinion on the subject is based on the Companies Act and English common law authorities, the latter of which are persuasive but not binding in the courts of the Cayman Islands. Under English authorities, circumstances in which a court would attribute personal liability to a shareholder are very limited, and include: (a) such shareholder expressly assuming direct liability (such as a guarantee); (b) the company acting as the agent of such shareholder; and (c) the company being incorporated by or at the behest of such shareholder for the purpose of committing or furthering such shareholder’s fraud, or for a sham transaction otherwise carried out by such shareholder. In the absence of these circumstances, we are of the opinion that a Cayman Islands’ court would have no grounds to set aside the limited liability of a shareholder.

Non-Assessable

In this opinion, the phrase “non-assessable” means, with respect to the Class A Ordinary Shares in the Company, that a shareholder shall not, solely by virtue of its status as a shareholder, be liable for additional assessments or calls on the Class A Ordinary Shares by the Company or its creditors (except in exceptional circumstances, such as involving fraud, the establishment of an agency relationship or an illegal or improper purpose or other circumstance in which a court may be prepared to pierce or lift the corporate veil).

5	Our examination of the Register of Writs cannot conclusively reveal whether or not there is:

	(a)	any current or pending litigation in the Cayman Islands against the Company; or

	(b)	any application for the winding up or dissolution of the Company or the appointment of any liquidator, trustee in bankruptcy or restructuring officer in respect of the Company or any of its assets,

as notice of these matters might not be entered on the Register of Writs immediately or updated expeditiously or the court file associated with the matter or the matter itself may not be publicly available (for example, due to sealing orders having been made). Furthermore, we have not conducted a search of the summary court. Claims in the summary court are limited to a maximum of CI $20,000.

Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We hereby consent to the incorporation by reference in this Registration Statement on Form S-1 pursuant to rule 462(b) under the Securities Act of 1933, as amended, of our report dated January 26, 2026, relating to the financial statements of ClearThink 1 Acquisition Corp. as of October 16, 2025 and for the period from September 11, 2025 (inception) through October 16, 2025, appearing in the Registration Statement on Form S-1, File No. 333-292967.

/s/ WithumSmith+Brown, PC

New York, New York

February 23, 2026

Calculation of Filing Fee Tables
S-1
Clearthink 1 Acquisition Corp.

Table 1: Newly Registered and Carry Forward Securities	☐Not Applicable

		Security Type	Security Class Title	Fee Calculation or Carry Forward Rule	Amount Registered	Proposed Maximum Offering Price Per Unit	Maximum Aggregate Offering Price	Fee Rate	Amount of Registration Fee
Newly Registered Securities
Fees to be Paid	1	Equity	Class A ordinary shares underlying rights included as part of the Units(1)(2)	457(o)	1,725,000	$ 10.00	$ 17,250,000.00	0.0001381	$ 2,382.22
Fees Previously Paid
Carry Forward Securities
Carry Forward Securities
			Total Offering Amounts:				$ 17,250,000.00		$ 2,382.22
			Total Fees Previously Paid:						$ 0.00
			Total Fee Offsets:						$ 0.00
			Net Fee Due:						$ 2,382.22

Offering Note

¹	(1) Estimated solely for the purpose of calculating the registration fee pursuant to Rule 457(o) under the Securities Act. (2) Pursuant to Rule 416 under the Securities Act, this registration statement shall also cover any additional shares of the registrant's securities that become issuable by reason of any share splits, share dividends or similar transactions

Table 2: Fee Offset Claims and Sources	☑Not Applicable

		Registrant or Filer Name	Form or Filing Type	File Number	Initial Filing Date	Filing Date	Fee Offset Claimed	Security Type Associated with Fee Offset Claimed	Security Title Associated with Fee Offset Claimed	Unsold Securities Associated with Fee Offset Claimed	Unsold Aggregate Offering Amount Associated with Fee Offset Claimed	Fee Paid with Fee Offset Source
Rules 457(b) and 0-11(a)(2)
Fee Offset Claims	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A
Fee Offset Sources	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A
Rule 457(p)
Fee Offset Claims	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A
Fee Offset Sources	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A

Table 3: Combined Prospectuses	☑Not Applicable

	Security Type	Security Class Title	Amount of Securities Previously Registered	Maximum Aggregate Offering Price of Securities Previously Registered	Form Type	File Number	Initial Effective Date
N/A	N/A	N/A	N/A	N/A	N/A	N/A	N/A