Enjoy a book (4)
I believe the answer is:
read
'enjoy a book' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for read that I've seen before include "Check, emend (proof)" , "what follows 18 [OMASUM] in a 17 [RUMINANT]" , "Speak" , "Looked at and understood" , "Stomach" .)