Mouth or face, slangily (6)
I believe the answer is:
kisser
I believe this is a double definition.
'mouth' is the first definition.
(I've seen this before)
'face slangily' is the second definition.
(I've seen this in another clue)
(Other definitions for kisser that I've seen before include "Mouth (slang)" , "Casanova" , "Skiers (anag.)" , "Slangy face of osculatory origin" , "Mouth (sl.)" .)