US citizen appearing periodically (3,6)

I believe the answer is:

new yorker

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'us citizen' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe you can see an association between them that I can't see?

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for new yorker that I've seen before include "humorous magazine" , "city dweller" , "Magazine - inhabitant of the Big Apple" , "Queens resident, possibly" , "One from the Bronx, perhaps" .)

I've seen this clue in The Globe and Mail.

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