Frequent shortening spoils books (5)
I believe the answer is:
haunt
'frequent' is the definition.
(I've seen this before)
'shortening spoils books' is the wordplay.
'shortening' means to remove the last letter.
'spoils' becomes 'haul' (I've seen this before).
'books' becomes 'NT' (New Testament).
'haul' with its final letter removed is 'hau'.
'hau'+'nt'='HAUNT'
(Other definitions for haunt that I've seen before include "Unhat (anag.)" , "Frequent (a place)" , "Visit as a ghost" , "Place regularly frequented" , "Keep appearing" .)