Liberal creature returned book (8)
I believe the answer is:
libretto
'book' is the definition.
(I know that libretto is a type of book)
'liberal creature returned' is the wordplay.
'liberal' becomes 'lib'.
'creature' becomes 'otter' (I've seen this before).
'returned' shows that the letters should be reversed in order.
'otter' reversed gives 'retto'.
'lib'+'retto'='LIBRETTO'
(Other definitions for libretto that I've seen before include "component of opera" , "Words set to music, especially opera" , "textbook" , "Text set to music in opera" , "Script for a musical drama" .)