City wall with banana on? (9)

I believe the answer is:

rotterdam

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'city' is the definition.
(Rotterdam is an example)

I can't explain the rest of the clue.

(Other definitions for rotterdam that I've seen before include "foreign city" , "Dutch city and port" , "Major world seaport at the mouth of the Meuse" , "city abroad" , "Netherlands port" .)

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