Not a flighty bird (7)

I believe the answer is:

penguin

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'bird' is the definition.
(penguin is a kind of bird)

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

(Other definitions for penguin that I've seen before include "Flightless seabird" , "King or emperor?" , "Black-and-white antarctic bird" , "Swimming bird" , "swimmer" .)

I've seen this clue in the Evening Standard.

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