To brief you about CLAT, it's conducted for two hours carrying 150 MCQs, each question is for one mark, and 0.25 mark is deducted for each incorrect attempt. It consists of sections such as comprehension-based questions from English Language,Current Affairs including General Knowledge,Legal Reasoning,Logical Reasoning, Quantitative Techniques
First of all make a timetable, be acquainted with paper pattern and syllabus which you can check out at https://consortiumofnlus.ac.in/clat-2021/ug-syllabus.html and devote time to each section accordingly.
For Language Comprehension, you can use Wren and Martin for grammar, and Norman Lewis's Word Power Made Easy to build vocabulary, also reading editorials section of The Hindu and The Indian Express will help you immediately to grasp the comprehension part along with enriching your vocabulary.
For General Knowledge and Current Affairs, you can go through magazines such as Pratiyogita Darpan, the best way to deal with dynamic portion is reading newspaper on a daily basis ,you can choose The Hindu or The Indian Express.For static GK part,you can use Lucent's GK. Also,you can search in Internet there are many sites which have compiled this in an organized manner pertaining to different subjects.
For Legal Reasoning, you can use Legal Aptitude and Legal Reasoning by A P Bhardwaj or Legal Awareness and Legal Reasoning by Pearson.
For Logical Reasoning, you can use any reasoning book such as Analytical Reasoning by M K Pandey or even Verbal and Non-Verbal Reasoning by RS Agarwal. try to get your concepts clear first and then practice in a steady manner.
For Quantitative Techniques, use Quantitative Aptitude by RS Aggarwal, you can also use NCERTs book to build the basic concepts,
Last but not the least visit the official website at https://consortiumofnlus.ac.in/ to know more details pertaining question paper format, sample paper and other such important aspects in regards to preparation of CLAT.