Criminal is led out in isolation (8)
I believe the answer is:
solitude
'isolation' is the definition.
(solitude is a kind of isolation)
'criminal is led out' is the wordplay.
'criminal' is an anagram indicator.
'is'+'led'+'out'='isledout'
'isledout' anagrammed gives 'SOLITUDE'.
'in' acts as a link.
(Other definitions for solitude that I've seen before include "Privacy" , "Lack of company" , "Absence of company" , "Isolated state - slide out (anag)" , "Lone state" .)