Answer:

arrear

Answer	Crossword Clue
ARREAR	Unpaid debt
ARREAR	Unfulfilled duty
ARREAR	Overdue thing

ARREAR	Delinquency word more commonly heard in the plural
ARREAR	Overdue debt
ARREAR	In ...: owing debts
ARREAR	Debt
ARREAR	Overdue payment
ARREAR	Balance due.
ARREAR	Part that's overdue.
ARREAR	Part overdue.

ARREAR	In ... (behind-hand).
ARREAR	That held in reserve.
ARREAR	In ... (behind in paying, working, etc.).
ARREAR	In ..., tardy in a way
ARREAR	Debtor's situation
ARREAR	In ... (behind in paying)
ARREAR	Unpaid bill
ARREAR	Something unpaid but due

ARREAR	In ... (behind)
ARREAR	In ... (behind in debt paying)
ARREAR	Overdue sum
ARREAR	State of lateness
ARREAR	Amount of debt, old-style
ARREAR	In ... (late, in law)
ARREAR	Overdue amount
ARREAR	Sum of money owed

ARREAR	Old-style debt