The boss controls the speed of the engine (8)

I believe the answer is:

governor

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'the boss' is the definition.
(I've seen this before)

I can't explain the remainder of the clue.

(Other definitions for governor that I've seen before include "One exercising authority" , "Device that controls, speed of an engine" , "Regulator; father" , "Ron, go run up the state head" , "Regulating device" .)

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

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