Mark for life (4)
I believe the answer is:
scar
'mark for life' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for scar that I've seen before include "Mark of former injury" , "Remnant of wound" , "nine [AL CAPONE] had to face" , "Evidence of an old injury" , "Steep cliff; skin mark" .)