Strikes back to fight verbally (4)
I believe the answer is:
spar
'fight verbally' is the definition.
(synonyms)
'strikes back' is the wordplay.
'strikes' becomes 'raps' ('rap' can be a synonym of 'strike').
'back' is a reversal indicator.
'raps' reversed gives 'SPAR'.
'to' is the link.
(Other definitions for spar that I've seen before include "Rafter, boom" , "Argue" , "quarrel" , "Box without punching hard" , "Translucent mineral" .)