Hey Vani.

Yes,  the materia of CLAT possible will be a good source for preparing Vocabulary for CLAT. The list of words in it will be good enough for your preparation. Along with that material you should make sure that you go through the previous year question papers and practice from there too. For an additional source, make sure you read editorial section of newspapers like The Hindu regularly, it will not only help you build a good vocabulary but also help you in the reading section for CLAT.

Best of luck