Confinement of prisoners with exercise given minimal time (10)
I believe the answer is:
constraint
'confinement' is the definition.
(I've seen this before)
'prisoners with exercise given minimal time' is the wordplay.
'prisoners' becomes 'cons'.
'with' says to put letters next to each other.
'exercise' becomes 'train' (training is a kind of exercising**).
'given' means one lot of letters go next to another.
'minimal' suggests taking the first letters.
The first letter of 'time' is 't'.
'cons'+'train'+'t'='CONSTRAINT'
'of' acts as a link.
(Other definitions for constraint that I've seen before include "force" , "restriction made" , "Restriction - in contrast (anag)" , "Limit - restriction" , "Limitation" .)