Unpaid bills (5)
'unpaid bills' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for debts that I've seen before include "Amounts owed" , "Outstanding sums" , "They're owed" , "Financial obligations" , "Monies owed" .)
(Other definitions for arrears that I've seen before include "In these, one is behind with payments" , "Ourtstanding payments" , "If in these, the money is overdue" , "Amount unpaid" , "Unpaid debts" .)