Students reviewed small mistakes (4-3)

I believe the answer is:

slip-ups

'mistakes' is the definition.
(I know this)

'students reviewed small' is the wordplay.
'students' becomes 'pupils' ('pupil' can be a synonym of 'student').
'reviewed' shows that the letters should be reversed in order.
'small' becomes 's' (abbreviation - e.g. clothes size).
'pupils' in reverse letter order is 'slipup'.
'slipup'+'s'='SLIP-UPS'

(Another definition for slip-ups that I've seen is " Errors".)

I've seen this clue in The Times.

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