Old wound (4)
I believe the answer is:
scar
'old wound' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for scar that I've seen before include "Craggy rock formation" , "Sign of old injury" , "Healed-cut mark" , "Injury mark - cliff" , "Steep cliff; skin mark" .)