Coppers to accept an imposed punishment (7)
I believe the answer is:
penance
'imposed punishment' is the definition.
'coppers to accept an' is the wordplay.
'coppers' becomes 'pence' (copper coins - pennies).
'to accept' is an insertion indicator.
'pence' enclosing 'an' is 'PENANCE'.
(Other definitions for penance that I've seen before include "Voluntary self-punishment" , "Punishment for religious wrongdoing" , "humiliating act" , "Self-inflicted punishment for wrongdoing" , "Punishment imposed for sin" .)