A kick (4)
I believe the answer is:
boot
'a kick' is the definition.
(I know that kick can be written as boot)
This is all the clue.
(Other definitions for boot that I've seen before include "Sturdy footwear" , "Kick; footwear" , "Sack" , "Hard kick (colloq.)" , "Hard kick; part of car" .)