Do business with, but clearly feel superior to (9)

I believe the answer is:

patronise

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'do business with' is the definition.
('do business with'->'patronize' is in my internal thesaurus and 'ize'->'ise')

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for patronise that I've seen before include "Talk down to" , "Frequent as customer" , "Give encouragement or treat with condescension" , "Finance" , "champion" .)

I've seen this clue in the Evening Standard.

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