Scrooge bound by promise, repents (5)
I believe the answer is:
miser
'scrooge' is the definition.
(Dickens' Ebenezer Scrooge is a miser)
'bound by promise repents' is the wordplay.
'bound by' says the answer is hidden in the clue (the answer is bound within the clue).
'MISER' is hidden within 'promise repents'.
(Other definitions for miser that I've seen before include "Mean-minded type" , "Penny-pincher" , "One sparing with money" , "Stingy hoarder" , "screw" .)