Mischief-maker, ringleader, and one child put in jail (8)
I believe the answer is:
imprison
'put in jail' is the definition.
(I've seen this before)
'mischief-maker ringleader and one child' is the wordplay.
'mischief maker' becomes 'imp' (I've seen this in other clues).
'ringleader' becomes 'r' (first letter of ring).
'and' says to put letters next to each other.
'one' becomes 'i' (Roman numeral).
'child' becomes 'son' (son is a kind of child**).
'imp'+'r'+'i'+'son'='IMPRISON'
(Other definitions for imprison that I've seen before include "Confine" , "Place in custody" , "Send down" , "Incarcerate" , "Put behind bars" .)