Lock up mischief-maker, revolutionary Irish boy (8)
I believe the answer is:
imprison
'lock up' is the definition.
(thesaurus)
'mischief-maker revolutionary irish boy' is the wordplay.
'mischief maker' becomes 'imp' (I've seen this in other clues).
'revolutionary' shows that the letters should be reversed in order.
'irish' becomes 'ir' (abbreviation).
'boy' becomes 'son' ('son' can be a synonym of 'boy'**).
'ir' written backwards gives 'ri'.
'imp'+'ri'+'son'='IMPRISON'
(Other definitions for imprison that I've seen before include "Put behind bars" , "Put in gaol" , "shut up" , "Put in jail" , "Incarcerate" .)