Stray from the proper route (3)

I believe the answer is:

err

'stray' is the definition.
(to err is to stray or go wrong)

'from the proper route' is the wordplay.
'from' says the answer is hidden in the clue.
'ERR' can be found hidden inside 'proper route'.

(Other definitions for err that I've seen before include "Go wrong" , "Drop a clanger" , "Bungle" , "do something you shouldn't" , "Boob" .)

I've seen this clue in the Evening Standard, The Globe and Mail and The Irish News.

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