Support teachers assessing work? They finish after everyone else (4,7)

I believe the answer is:

back markers

'they finish after everyone else' is the definition.
(people coming at the end of a race)

'support teachers assessing work?' is the wordplay.
'support' becomes 'back' (backing is a kind of supporting).
'teachers assessing work?' becomes 'markers'.
'back'+'markers'='BACK MARKERS'

I've seen this clue in The Guardian.

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