Derisive look (5)
I believe the answer is:
sneer
'derisive look' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sneer that I've seen before include "Curl one's lip" , "Show contempt with scornful expression or words" , "Show contempt by contorting the face" , "Express cynical contempt" , "Derisive remark" .)