Verge on answer, nevertheless (4)
I believe the answer is:
abut
'verge on' is the definition.
(I've seen this in another clue)
'answer nevertheless' is the wordplay.
'answer' becomes 'a' (abbreviation eg in Q and A).
'nevertheless' becomes 'but' (I've seen this before).
'a'+'but'='ABUT'
(Other definitions for abut that I've seen before include "Lie next to" , "Be next to -- share a boundary" , "Adjoin, press up against" , "Join" , "Be next door to" .)