Contemptuous expression (5)
I believe the answer is:
sneer
'contemptuous expression' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for sneer that I've seen before include "Curl one's lip" , "Scoff, scorn" , "Express cynical contempt" , "Contemptuous remark" , "Contemptuous expression" .)