Enter a clue or pattern or both:
The Clue
Promise of a sort (3 letter answer)
The Answer
IOU
Tags
Notes
The answer IOU is seen frequently, appearing about once every 90 puzzles.
Related Clues
Chit
Marker
Cash substitute
Chit in a pot
Debenture, basically
Debt acknowledgment
Debt doc
Debt initials
Debt marker
Debt memo
Debtor's letters
Debtor's note
Debtor's promise
Gambler's mark
Gambling note
Letters on a chit
Letters of credit
Letters of credit?
Letters of debt
Marker letters
Marker, for short
Paper in a pot
Promise to pay
Unpopular slip
Indicator of shortness, for short
Item in a poker pot
Money substitute, for short
Note from a busted person
Note traded for bills
Note from one who's shy
Paper in lieu of payment
Definition
IOU as a noun:
1. an informal debt instrument; representing `I owe you'