conscience-stricken (8)
I believe the answer is:
penitent
'conscience-stricken' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for penitent that I've seen before include "Expressing sorrow for one's sins" , "Remorseful" , "Feeling remorse" , "Feeling regret for one's sins" , "I'm sorry" .)