Force prisoners to study (9)

I believe the answer is:

constrain

'force' is the definition.
(thesaurus)

'prisoners to study' is the wordplay.
'prisoners' becomes 'cons'.
'to study' becomes 'train' (training is a kind of studying).
'cons'+'train'='CONSTRAIN'

(Other definitions for constrain that I've seen before include "Hold back - non-racist (anag)" , "Lock up" , "Confine, limit" , "Compel; constrict" , "Severely restrict" .)

I've seen this clue in The Independent.

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