Top recommendation by a US wine region (4)

I believe the answer is:

napa

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'wine region' is the definition.
(I've seen this in another clue)

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

(Other definitions for napa that I've seen before include "soft skin" , "Californian valley, famous for wine" , "California wine valley" .)

I've seen this clue in The Irish Times.

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