Shut up again? Feel remorse (6)
I believe the answer is:
repent
'feel remorse' is the definition.
(I've seen this before)
'shut up again?' is the wordplay.
I cannot really see how this works, but
'again?' could be 're' (prefix meaning 'again') and 're' is present in the answer.
'shut up' could be 'pent' (synonyms) and 'pent' is found within the answer.
This accounts for all the letters.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for repent that I've seen before include "creeping along the ground" , "Turn away from sin" , "Be sorry for - . . . . . . ye sinners" , "Be contrite, ye sinners" , "Be sorry for wrongdoing" .)