1) Beholden one 2) Chit writer 3) Credit-card user 4) Debt-ridden one 5) Debtor 6) Debtor, old-style 7) Endebted individual 8) Hamlet in Hampshire 9) One in a hole 10) One in arrears 11) One in debt 12) One in the red 13) One making markers 14) One seeing a lot of red 15) One who charges 16) One who has debts 
over, rather
Over
over.