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' indicates the answer is hidden within the clue.
'ERR' is hidden in the letters of '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 Globe and Mail, the Evening Standard and The Irish News.

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