Corrupt books seen after ten years (8)
I believe the answer is:
decadent
'corrupt' is the definition.
(I've seen this in another clue)
'books seen after ten years' is the wordplay.
'books' becomes 'NT' (New Testament).
'seen after' means one lot of letters go next to another.
'ten years' becomes 'decade' (a decade is ten years).
'nt' after 'decade' is 'DECADENT'.
(Other definitions for decadent that I've seen before include "Decanted, being corrupt and immoral" , "Debauched" , "Fin-de-sicle" , "Culturally in decline" , "base?" .)