Head striker’s spread (6)
I believe the answer is:
butter
I believe this clue is a double definition.
'head striker's' is the first definition.
(an animal that head-butts)
'spread' is the second definition.
(I've seen this before)
(Other definitions for butter that I've seen before include "Edible fat" , "Type of toffee" , "goat?" , "Fat - type of fly" , "Spread derived from cream" .)