Note about illustrious French city (8)
I believe the answer is:
grenoble
'french city' is the definition.
(city in southeastern France)
'note about illustrious' is the wordplay.
'note' becomes 'g' (musical note).
'about' becomes 're' ('re' means regarding or about).
'illustrious' becomes 'noble' (I've seen this in another clue).
'g'+'re'+'noble'='GRENOBLE'
(Other definitions for grenoble that I've seen before include "French city and skiing centre" , "French Alpine city" , "City of southeast France" , "City of SE France" , "City of south-eastern France" .)