Capital way to spell "AS"? (6)

I believe the answer is:

athens

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'capital' is the definition.
(capital of Greece)

I cannot understand how the rest of the clue works.

(Other definitions for athens that I've seen before include "Capital of Greece" , "EU capital" , "6 capital" , "City in which 13 Across founded school" , "Hasten to European capital" .)

I've seen this clue in the Sydney Morning Herald.

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