Criminal sort in jail's last bit of snout (7)
I believe the answer is:
nostril
'snout' is the definition.
(thesaurus)
'criminal sort in jail's last bit of' is the wordplay.
'criminal' is an anagram indicator.
'last bit of' suggests the final letters.
The last letter of 'jail' is 'l'.
'sort'+'in'='sortin'
'sortin' is an anagram of 'nostri'.
'nostri'+'l'='NOSTRIL'
(Other definitions for nostril that I've seen before include "Nose hole" , "Nasal passageway" , "Breathing opening for a human" , "Breathing space" , "Nasal cavity" .)