Injury mark (4)
I believe the answer is:
scar
'injury mark' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for scar that I've seen before include "Bare rocky cliff - injury" , "Craggy rock formation" , "Disfigure(ment)" , "Mark left by injury" , "Evidence of an old cut?" .)