'Gay Lib' -- the novel (6)
I believe the answer is:
blithe
'gay' is the definition.
(thesaurus)
'lib the novel' is the wordplay.
'novel' is an anagram indicator.
'lib'+'the'='libthe'
'libthe' is an anagram of 'BLITHE'.
(Other definitions for blithe that I've seen before include "Merry" , "Happy, joyous" , "Gay" , "Joyful and unconcerned" , "Light-hearted and good-humoured" .)