A blow or a kick (4)
I believe the answer is:
bang
I believe this clue is a double definition.
'a blow' is the first definition.
(bang is a kind of blow)
'a kick' is the second definition.
('bang' can be a synonym of 'kick')
'or' is the link.
(Other definitions for bang that I've seen before include "Sudden impact" , "Loud noise; fringe" , "Strike violently" , "Completely modern" , "Explosion; hair fringe" .)