Show contempt (5)
I believe the answer is:
sneer
'show contempt' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sneer that I've seen before include "Smile contemptuously" , "Curl one's lip" , "Contemptuous or mocking smile" , "Contemptuous expression" , "Speak contemptuously" .)