Crosophile en ville near Toulouse? Not with this perhaps (5)
I believe the answer is:
alibi
'not with this perhaps' is the definition.
The definition suggests a singular noun which matches the answer.
'crosophile en ville near toulouse?' is the wordplay.
'crosophile' becomes 'i' (I can't explain this - if you can you should give a lot more credence to this answer).
'en' means one lot of letters goes inside another (French for \'in\').
'ville near toulouse?' becomes 'albi' (French commune).
'i' inserted within 'albi' is 'ALIBI'.
(Other definitions for alibi that I've seen before include "Plea of absence" , "Legal proof of innocence" , "Story confirming innocence" , "Evidence one was elsewhere at time of crime" , "Evidence that the accused could not have been guilty" .)