Enter a clue or pattern or both:
The Clue
Payment promise (3 letter answer)
The Answer
IOU
Tags
Notes
The answer IOU is seen frequently, appearing about once every 90 puzzles.
Related Clues
Chit
Marker
Promise
Account receivable
Cash alternative
Debt chit
Debt doc
Debt memo
Debtor's letters
Debtor's note
Debtor's promise
Gambler's mark
Gambler's marker
Gambling note
Gambling tab
Letters of credit
Marker letters
Marker, of sorts
Note of indebtedness
Obligatory letters
Payment initials
Promissory note
Unpopular slip
Money substitute, for short
Note traded for bills
Note from one who's shy
Paper in a poker pot
Part of a poker pot
Promise in a poker pot
Last poker bet, sometimes
Note to be used later
Note in a poker game, e.g.
This may incur vigorish
Definition
IOU as a noun:
1. an informal debt instrument; representing `I owe you'