Person demanding payment for a warhorse once (7)

I believe the answer is:

charger

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'person demanding payment' is the definition.
(someone who charges or asks for payment)

I cannot understand how the rest of the clue works.

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(Other definitions for charger that I've seen before include "What Richard III wanted, perhaps" , "One may provide juice" , "He doesn't mean it to be a gift" , "Cavalry horse - used on battery" , "Type of platter" .)

I've seen this clue in The Times.

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