Navigation aid (5)
'navigation aid' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for radar that I've seen before include "Method of detection" , "Equipment for locating objects" , "Locator that uses a microwave echo" , "Radio device for tracking distant objects" , "System for detecting things using radio waves" .)
'navigation aid' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sonar that I've seen before include "Echo-location system" , "Echo-sounding equipment" , "Underwater location equipment" , "What a near-blind creature uses" , "echo device" .)