For CLAT PG, the subjects that are covered are Constitution, Jurisprudence, Tort, Criminal law, Administrative law, IPR, Contract and Public International law. All these subjects are important for answering subjective and objective type of questions. Few books that can help you are:

Constitution:

Constitution book by V.N.Shukla

Constitution book by J.N. Pandey

Multiple Choice Questions on Constitution of India

Jurisprudence:

Jurisprudence and Legal theory by V.D.Mahajan

Studies in Jurisprudence and legal theory by N.V.Parajape

Decoding the Jurisprudence

Tort:

Law of Torts by B.M.Gandhi

IPC;

IPC bu K.D.Gaur

Contract:

Law of Contract and Specific Relief

International Law:

Text book on International law by Dr. Rakesh Kumar Singh

You can also benefit from the previous sample papers available at: https://law.careers360.com/download/sample-papers/clat-pg-question-paper-and-answer-key-2019?icn=exam-view&ici=exam-view_related-ebook-samplepaper