Bill's arrived with agency (7)
I believe the answer is:
invoice
'bill's' is the definition.
(invoicing is a kind of billing)
'arrived with agency' is the wordplay.
'arrived' becomes 'in' (I've seen this in other clues).
'with' says to put letters next to each other.
'agency' becomes 'voice' (as in an agency acting as a community's voice).
'in'+'voice'='INVOICE'
(Other definitions for invoice that I've seen before include "Account; bill" , "Demand for sum due" , "Bill (fit to sing?)" , "Statement of account" , "ask for payment" .)