Prisoner to invite ridicule (8)
I believe the answer is:
contempt
'ridicule' is the definition.
(I've seen this before)
'prisoner to invite' is the wordplay.
'prisoner' becomes 'con' (abbreviation for 'convict').
'to invite' becomes 'tempt' (tempting is a kind of inviting).
'con'+'tempt'='CONTEMPT'
(Other definitions for contempt that I've seen before include "Disregard for the rules of a court of law" , "Disobedience to the rule of court of law" , "Wilful disrespect of authority" , "Feeling of dislike for, perhaps of court?" , "Feeling of disdain, sometimes of court" .)