Crossword Genius

Radar perhaps surprisingly protected after power cut (8)

Ross

I believe the answer is:

detector

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'radar' is the definition.
(thesaurus)

I can't explain the remainder of the clue.

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(Other definitions for detector that I've seen before include "Device warning of, eg, smoke" , "Sensor" , "Device for monitoring hazards" , "Electronic device" .)

I've seen this clue in The Independent.
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