In due course answer line on the side (7)
I believe the answer is:
lateral
'on the side' is the definition.
(lateral means located on the side)
'in due course answer line' is the wordplay.
'in due course' becomes 'later' (I've seen this before).
'answer' becomes 'a' (abbreviation eg in Q and A).
'line' becomes 'l' (used when specifying particular lines from a poem).
'later'+'a'+'l'='LATERAL'
(Other definitions for lateral that I've seen before include "This kind of sideways thinking does not use conventional logic" , "This kind of thinking is unconventional" , "Shoot" , "Possibly right" , "Way of thinking" .)