Turn back in French street for scoundrel (5)
I believe the answer is:
rogue
'for scoundrel' is the definition.
(rogue is a kind of scoundrel)
'turn back in french street' is the wordplay.
'turn' becomes 'go' (a person's move in a board game).
'back' says the letters should be written backwards.
'in' means one lot of letters goes inside another.
'french street' becomes 'rue' (French for street or road).
'go' written backwards gives 'og'.
'og' inserted within 'rue' is 'ROGUE'.
(Other definitions for rogue that I've seen before include "Miscreant" , "Baddy" , "Chap in gallery" , "Scoundrel, knave" , "Villain - freak" .)