A Bond villain unmasked as Italian banker (4)

I believe the answer is:

arno

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'banker' is the definition.
(I've seen this before)

I can't explain the remainder of the clue.

(Other definitions for arno that I've seen before include "River of 4 down?" , "River in central Italy" , "River of 11 across" , "Pisa's river" , "River flowing through Florence and Pisa" .)

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

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