In case of theft, miscarriage of justice is criminal (9)
I believe the answer is:
terrorist
'criminal' is the definition.
(thesaurus)
'in case of theft miscarriage of justice is' is the wordplay.
'in' is an insertion indicator.
'case of' suggests removing the centre (outsides of).
'miscarriage of justice' becomes 'error' (I've seen this before).
'theft' with its middle taken out is 'tt'.
'error'+'is'='erroris'
'tt' enclosing 'erroris' is 'TERRORIST'.
(Other definitions for terrorist that I've seen before include "Person who uses violence for political purposes, such as member of Al Qaeda" , "User of violence for political ends" , "User of violence to intimidate governments" , "one likely to cause mayhem?" , "violent revolutionary" .)