Memorised books by poet (6)
I believe the answer is:
learnt
'memorised' is the definition.
(to memorise is to learn by heart)
'books by poet' is the wordplay.
'books' becomes 'nt' (New Testament).
'by' is a charade indicator (letters next to each other).
'poet' becomes 'lear' (poet Edward Lear).
'nt' after 'lear' is 'LEARNT'.
(Other definitions for learnt that I've seen before include "Aquired knowledge or skill" , "Studied" , "Heard" , "Acquired knowledge or skill" , "Picked up" .)