Attacker’s comparatively quick removing pawn (6)
I believe the answer is:
raider
'attacker's' is the definition.
(thesaurus)
'comparatively quick removing pawn' is the wordplay.
'comparatively quick' becomes 'rapider' ('rapid' can be a synonym of 'quick').
'removing' suggests deleting specific letters.
'pawn' becomes 'p'.
'rapider' with 'p' taken away is 'RAIDER'.
(Other definitions for raider that I've seen before include "One making incursion" , "One who makes surprise attack, perhaps to steal" , "One making a rapid surprise attack" , "Armed insurgent" , "One attacks" .)