Fleshy fold of mouth tissue (3)
I believe the answer is:
lip
'fleshy fold of mouth tissue' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for lip that I've seen before include "In slang, impudent talk" , "Insolence (slang)" , "Top edge of a vessel" , "Aural impudence" , "Brim" .)