Down-to-earth New Zealand birds (5)

I believe the answer is:

kiwis

I'm a little stuck... Click here to teach me more about this clue!

'new zealand birds' is the definition.
(I've seen this in another clue)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for kiwis that I've seen before include "NZ birds or team" , "Flightless birds and fruits" , "Flightless birds of New Zealand" .)

I've seen this clue in the Evening Standard.

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