Wound reminder (4)
I believe the answer is:
scar
'wound reminder' 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 "Limestone cliff or outcrop" , "Mark of former injury" , "Effect of unpleasant experience" , "Mark of a wound remaining on the skin" , "Old-wound mark" .)