Coppers in out-of-date account (3,4)
I believe the answer is:
old bill
'coppers' is the definition.
(I've seen this before)
'out-of-date account' is the wordplay.
'out-of-date' becomes 'old'.
'account' becomes 'bill' (billing is a kind of accounting).
'old'+'bill'='OLD BILL'
'in' is the link.
(Other definitions for old bill that I've seen before include "Policeman" , "forgotten account" , "Police (slang)" , "previous charges" , "pound note?" .)