Coppers welcoming an act of contrition (7)
I believe the answer is:
penance
'act of contrition' is the definition.
(as in doing penance)
'coppers welcoming an' is the wordplay.
'coppers' becomes 'pence' (I've seen this before).
'welcoming' indicates putting letters inside (in sense of 'inviting in').
'pence' enclosing 'an' is 'PENANCE'.
(Other definitions for penance that I've seen before include "Expression of sorrow for sin" , "Punishment imposed for sin" , "Act of contrition" , "Punishment for wrongdoing, by religion perhaps" , "Voluntary self-abasement" .)