Head to show contempt physically? (4)
I believe the answer is:
spit
'head' is the definition.
(thesaurus)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for spit that I've seen before include "Eject with violence" , "Narrow strip of land almost surrounded by water" , "A spade's depth, in earth" , "Skewer; headland" , "little light rain" .)