C-section mark (4)
I believe the answer is:
scar
'c-section mark' 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 "Mark on body or tree" , "Bare rocky cliff - injury" , "Mark from a wound left on the skin" , "Healed-cut mark" , "Nasty mark" .)