Scornful expression (5)
I believe the answer is:
sneer
'scornful expression' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for sneer that I've seen before include "Curl one's lip" , "Show contempt by contorting the face" , "Express cynical contempt" , "Contemptuous remark" , "Contemptuous expression" .)