Fish-eater in restaurant initially crazy about port (9)

I believe the answer is:

rotterdam

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'port' is the definition.
(I know that Rotterdam is a port)

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

(Other definitions for rotterdam that I've seen before include "Netherlands port" , "European port" , "Dutch city and port" , "Major North Sea port - tarred tom (anag)" , "Major world seaport at the mouth of the Meuse" .)

I've seen this clue in The Times.

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