Busy airport (3)

I believe the answer is:

'busy airport' is the definition.
(I've seen this in another clue)

This is the entire clue.

(Other definitions for hub that I've seen before include "Centre (of network)" , "Focus" , "Centre of wheel" , "Centre or axis" , "Central part of a car wheel" .)

I've seen this clue in the USA Today, the King Feature Syndicate, The New York Times, The Wall Street Journal and The Mirror.

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.