Fast-running flightless bird of South America (4)

I believe the answer is:

rhea

(Other definitions for rhea that I've seen before include "S. Amer. flightless bird" , "Grounded bird" , "New World ostrich" , "It can't fly" , "Moon" .)

I've seen this clue in 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.