Compunction (7)
I believe the answer is:
remorse
'compunction' is the definition.
(I know that compunction can be written as remorse)
This is all the clue.
(Other definitions for remorse that I've seen before include "Gnawing pain of conscience" , "Guilt for a wrong deed" , "Regret or sorrow for wrong-doing" , "regrets" , "display of conscience" .)