Feeling of guilt (6)
I believe the answer is:
twinge
'feeling of guilt' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for twinge that I've seen before include "Slight pang, maybe of conscience" , "Spasm" , "Slight pain (of conscience?)" , "Small pain eg from conscience" , "Pinch" .)