Crossword Genius

Detection system (5)

Ross

I think it could be either:

radar

sonar

'detection system' is the definition.
(sonar is a system that detects using sound waves)

This is all the clue.

(Other definitions for sonar that I've seen before include "location device" , "Detection system at sea" , "Method of echolocation" , "Device for detecting objects used in arson" , "Underwater detection system" .)

I've seen this clue in the Penny Press, The Telegraph, the Evening Standard and The Times.
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