Lipstick smudge (5)
I believe the answer is:
smear
'lipstick smudge' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for smear that I've seen before include "Blot or daub" , "Smother" , "sample on slide" , "Greasy or sticky mark" , "unpleasant mark" .)