Related Clues:

• Marker, of sorts
• Gambling note
• Promising letters
• Commitment to pay
• Brief promise?
• Chit sheet
• Gambler's note, slangily
• Debtor's pledge
• Debt evidence
• Gambler's initialism
• Letters from a person who's shy?
• Signed promise to pay
• Bettor's note
• Payment promise
• "Pay you next time!"