Crossword Genius

Alert operative (8,2)

Ross

I believe the answer is:

switched on

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

I don't understand the rest of the clue.

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(Other definitions for switched on that I've seen before include "Aware" , "lights working?" , "Emotionally aroused" , "Up to date" , "Alert" .)

I've seen this clue in The Times.
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