Mark’s shock when failing to finish (4)
I believe the answer is:
scar
'mark's shock' is the definition.
The answer and definition can be both states of affairs as well as being singular nouns.
I also know that 'mark' relates to this answer.
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for scar that I've seen before include "Disfigure" , "area of wound" , "reef" , "sign of damage" , "Mark of a wound remaining on the skin" .)