Radar not working to locate one Aussie truck (4,5)

I believe the answer is:

road train

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

I cannot understand how the remainder of the clue works.

(Other definitions for road train that I've seen before include "truck with trailers" , "means of moving freight" , "Antipodean lorry with trailers" , "See Aussie truck" .)

I've seen this clue in The Sun.

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