Picked up writer's books (6)
I believe the answer is:
learnt
'picked up' is the definition.
(pick up can mean to learn or discover)
'writer's books' is the wordplay.
'writer' becomes 'lear' (I have seen 'comic writer' mean 'lear' so perhaps 'writer' could also mean 'lear').
'books' becomes 'NT' (New Testament).
'lear'+'nt'='LEARNT'
(Other definitions for learnt that I've seen before include "Gained knowledge or skill" , "Heard" , "Studied" , "Gathered" , "Came to know" .)