Mark's out of mascara (4)
I believe the answer is:
scar
'mark's' is the definition.
(mark left by an injury)
'of mascara' is the wordplay.
'of' says the answer is hidden in the clue.
'SCAR' can be found hidden inside 'mascara'.
'out' acts as a link.
(Other definitions for scar that I've seen before include "Injury mark - cliff" , "area of wound" , "Gordale - - , Yorks" , "Trace of an old injury" , "Disfigure" .)