Writer not into books originally (3)
I believe the answer is:
nib
'writer' is the definition.
(something which writes)
'not into books originally' is the wordplay.
'originally' suggests taking the first letters.
The initial letters of 'not into books' is 'NIB'.
(Other definitions for nib that I've seen before include "writer" , "Writing tip of old pen" , "Pen's point" , "Point of an old-fashioned pen" , "Pen-tip" .)