Rat run sent back through Parisian thoroughfare (5)
I believe the answer is:
rogue
'rat' is the definition.
(thesaurus)
'run sent back through parisian thoroughfare' is the wordplay.
'run' becomes 'go' (both can mean to function or work).
'sent back' says the letters should be written in reverse.
'through' is an insertion indicator (inserted letters go through the word).
'parisian thoroughfare' becomes 'rue' (I can't justify this - if you can you should give a lot more credence to this answer).
'go' backwards is 'og'.
'og' placed within 'rue' is 'ROGUE'.
Can you help me to learn more?
(Other definitions for rogue that I've seen before include "Old Greek" , "One dishonest" , "Miscreant" , "Fraud" , "Stray" .)