Clarity from Sicily -- it condemned imprisoning politician (10)
I believe the answer is:
simplicity
'clarity' is the definition.
(thesaurus)
'sicily it condemned imprisoning politician' is the wordplay.
'condemned' is an anagram indicator.
'imprisoning' is an insertion indicator.
'politician' becomes 'mp'.
'sicily'+'it'='sicilyit'
'sicilyit' with letters rearranged gives 'silicity'.
'silicity' enclosing 'mp' is 'SIMPLICITY'.
'from' acts as a link.
(Other definitions for simplicity that I've seen before include "Lack of affectation or pretence" , "Ease" , "Clarity" , "Couldn't be easier!" , "Facility, easiness" .)