Navigation aid that looks both ways (5)

I believe the answer is:

radar

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This clue could be a double definition.

'navigation aid that looks' is the first definition.
'radar' can be an answer for 'navigation' (thesaurus). I am unsure of the rest of the definition.

'both ways' is the second definition.

Can you help me to learn more?

(Other definitions for radar that I've seen before include "Gluttony" , "Ranging system" , "What shows range" , "Radio detection system" , "System for detecting things using radio waves" .)

I've seen this clue in The Mirror and The Daily Express.

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