A teacher is wrong (5)

I believe the answer is:

amiss

'is wrong' is the definition.
('amiss' can be a synonym of 'wrong')

'a teacher' is the wordplay.
'teacher' becomes 'miss' (I've seen this before**).
'a'+'miss'='AMISS'

(Other definitions for amiss that I've seen before include "Fallacious" , "Mistaken" , "Haywire" , "astray" , "Unsuitable" .)

I've seen this clue in The Times.

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