Opponent learning code bored by books (4)
I believe the answer is:
anti
'opponent' is the definition.
(someone opposed to something)
'learning code bored by books' is the wordplay.
'learning code' becomes 'ai' (I am not sure about this - if you are sure you should believe this answer much more).
'bored by' means one lot of letters goes inside another (to bore something can mean to drill into it).
'books' becomes 'NT' (New Testament).
'ai' placed around 'nt' is 'ANTI'.
Can you help me to learn more?
(Other definitions for anti that I've seen before include "Opposed to followers of Hitler" , "One who is against (something)" , "Definitely not pro" , "Naysayer" , "Negative vote" .)