Repentant, eh? (5)
I believe the answer is:
sorry
'repentant' is the definition.
('sorry' can be similar in meaning to 'repentant')
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for sorry that I've seen before include "pathetic!" , "Rueful" , "Penitent; regrettable" , "My apologies!" , "Common apology" .)