Athletic bird? (7)

I believe the answer is:

harrier

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'bird?' is the definition.
(harrier is a kind of bird)

I don't understand the rest of the clue.

(Other definitions for harrier that I've seen before include "jump jet" , "Bird - dog - plane" , "Hare hound" , "that flies!" , "Short-winged hawk" .)

I've seen this clue in the Evening Standard.

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