The Swiss fly a square one (4)

I believe the answer is:

flag

(Other definitions for flag that I've seen before include "Droop; iris" , "slow down" , "National standard" , "Rectangular piece of fabric used as a signalling device" , "Iris; ensign" .)

I've seen this clue in The New York Times.

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.