Contemptuous smile (5)
I believe the answer is:
sneer
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">contemptuous smile</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for sneer that I've seen before include "Show contempt by contorting the face" , "Be derisive; Sheridan's Critic" , "Curl one's lip" , "Contemptuous expression" , "Taunt" .)