Make mistake in computer routine (3)

I believe the answer is:

err

'make mistake' is the definition.
(to err is to make an error)

'in computer routine' is the wordplay.
'in' says the answer is hidden in the clue.
'ERR' is hidden within 'computer routine'.

(Other definitions for err that I've seen before include "Go astray" , "Blunder" , "Leave the straight and narrow" , "Be incorrect" , "Transgress" .)

I've seen this clue in The Sun.

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