Navigation aid looking both ways? (5)
I believe the answer is:
radar
This could be a double definition.
'navigation' is the first definition.
(thesaurus)
'aid looking both ways?' is the second definition.
'radar' can be an answer for 'aid' (I have seen 'Navigational aid ' mean 'radar' so perhaps 'aid' could also mean 'radar'). I'm unsure of the 'looking both ways?' bit.
Can you help me to learn more?
(Other definitions for radar that I've seen before include "Range-finding and detection system" , "System for pinpointing ships and aircraft" , "Instrument to detect and track distant objects" , "Locator that uses a microwave echo" , "What shows range" .)