Feel remorse over (3)
I believe the answer is:
rue
'feel remorse over' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for rue that I've seen before include "Swann's way?" , "Feel bad" , "Regret in a French street" , "At one time, pity" , "Regret or repent" .)