Fish and tea seller in New York (9)

I believe the answer is:

chavender

I'm a little stuck... Click here to teach me more about this clue!

'seller in new york' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'fish and tea' is the wordplay.
'fish' becomes 'vender' (I can't justify this - if you can you should believe this answer much more).
'and' is a charade indicator (letters next to each other).
'tea' becomes 'cha' (cha is a type of tea).
'vender' put after 'cha' is 'CHAVENDER'.

Can you help me to learn more?

I've seen this clue in The Guardian.

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