Runner bound to lose power (3)

I believe the answer is:

ski

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'runner' is the definition.
(something which 'runs', ie moves quickly on snow)

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for ski that I've seen before include "Winter sport item" , "go uphill? Probably not!" , "Alpine runner" , "What one might do in Alps" , "Go downhill rapidly" .)

I've seen this clue in The Times.

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