Suggestive grin (4)
I believe the answer is:
leer
'suggestive grin' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for leer that I've seen before include "Give lascivious look" , "unpleasant look" , "Look suggestively" , "Suggestive or sneering look" , "Stare suggestively" .)