Western supporter hasn't started fight (7)
I believe the answer is:
wrestle
'fight' is the definition.
(I know that wrestle is a more specific form of the action battle)
'western supporter hasn't started' is the wordplay.
'western' becomes 'w' ().
'supporter' becomes 'trestle' (I've seen this before).
'hasn't started' means to remove the first letter.
'trestle' with its initial letter removed is 'restle'.
'w'+'restle'='WRESTLE'
(Other definitions for wrestle that I've seen before include "Struggle, grapple" , "Fight - get to grips (with)" , "Grapple; strive" , "Fight; struggle" , "Grapple on canvas" .)