Somebody one's looking after for a fee (6)

I believe the answer is:

charge

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'a fee' is the definition.
(I've seen this in another clue)

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

(Other definitions for charge that I've seen before include "Attack - cost" , "Accuse - rush - request payment" , "Demand price; accuse" , "Price for a service" , "15 - or required payment" .)

I've seen this clue in the Evening Standard.

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