Crossword Genius

Promotion from flier - 1/3 off! (4)

Ross

I believe the answer is:

puff

I'm a little stuck... Click here to teach me more about this clue!

'promotion' is the definition.
(I've seen this before)

I don't understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for puff that I've seen before include "Drag on fag; be out of breath" , "out of which pants come?" , "Light pastry; advert" , "Gasp" , "plug" .)

I've seen this clue in The Guardian.
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.