Judge was taken ill in prison (6)
I believe the answer is:
jailed
'in prison' is the definition.
(thesaurus)
'judge was taken ill' is the wordplay.
'judge' becomes 'J' (abbreviation for judge).
'was taken ill' becomes 'ailed' (to ail is to be ill).
'j'+'ailed'='JAILED'
(Other definitions for jailed that I've seen before include "Incarcerated" , "in jug" , "Put away" .)