Sulky expression (4)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
pout
'sulky expression' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for pout that I've seen before include "shows disappointed face" , "Sullen expression" , "Moue - sulk" , "Look miffed" , "Sulky (or sexy?) expression" .)