Toothy look (4)
I believe the answer is:
grin
'toothy look' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for grin that I've seen before include "Facial expression showing amusement or pleasure" , "Smile while pulling back the lips" , "Beam" , "Facial expression, usually of pleasure" , "Happy expression" .)