Crossword clue: a small adhesive token stuck on a letter or package to indicate that that postal fees have been paid

The most common answer is postage (7 letters).

2 answers found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).

Possible answers

postage 7 letters wn-def

a small adhesive token stuck on a letter or package to indicate that that postal fees have been paid

stamp 5 letters wn-def

to mark, or produce an imprint in or on something