School again discover Greek coin before start of excavation (2-7)

I believe the answer is:

re-educate

'school again' is the definition.
(I've seen this before)

'discover greek coin before start of excavation' is the wordplay.
'discover' says to take the centre (I've seen 'discovered' mean this (dis-covered - outer letters removed)).
'coin' becomes 'ducat' (ducat is a kind of coin).
'before' is a charade indicator (letters next to each other).
'start of' says to take the initial letters.
The centre of 'greek' is 'ree'.
The initial letter of 'excavation' is 'e'.
'ree'+'ducat'+'e'='RE-EDUCATE'

I've seen this clue in The Independent.

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