Groucho-type look
I believe the answer is:
leer
'groucho-type look' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for leer that I've seen before include "Give lascivious look" , "Stare suggestively" , "Lascivious gaze" , "Suggestive or sneering grin" , "Gaze lasciviously at" .)