Fashionable area enveloped by evil -- to criminal that's pure (9)
I believe the answer is:
inviolate
'pure' is the definition.
(thesaurus)
'fashionable area enveloped by evil to criminal' is the wordplay.
'fashionable' becomes 'in' ('in' can be similar in meaning to 'fashionable').
'area' becomes 'a' (maths abbreviation).
'enveloped by' is an insertion indicator.
'criminal' indicates an anagram.
'evil'+'to'='evilto'
'evilto' anagrammed gives 'violte'.
'a' going within 'violte' is 'violate'.
'in'+'violate'='INVIOLATE'
'that's' acts as a link.
(Other definitions for inviolate that I've seen before include "completely untouched" , "not to be touched" , "unspoiled" , "Undamaged" , "Free from injury" .)