Post office purchase (9)

I think it could be either:

Which length description are you looking for?:

stamp

'post office purchase' is the definition.
(I've seen this in another clue)

This is the entire clue.

(Other definitions for stamp that I've seen before include "Impress; postage sticker" , "Bring foot down hard" , "Official mark; bang (foot)" , "contributions?" , "Postage paid label" .)

I've seen this clue in the USA Today.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.