Controls and supplies with energy (6)

I believe the answer is:

powers

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'supplies with energy' is the definition.
(I've seen this before)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for powers that I've seen before include "Supplies with energy" , "Countries in terms of their world influence" , "The ...... that be are people in authority" .)

I've seen this clue in The Globe and Mail.

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