Advance in French vehicle going round centre of Bourges (8)
I believe the answer is:
encroach
'advance' is the definition.
(encroaching is a kind of advancing)
'in french vehicle going round centre of bourges' is the wordplay.
'in french' becomes 'en' ('en' can be French for 'in' e.g. en France).
'vehicle' becomes 'coach' (coach is a kind of vehicle**).
'going round' indicates putting letters inside.
'centre of' indicates the central letters.
The middle letter of 'bourges' is 'r'.
'coach' going around 'r' is 'croach'.
'en'+'croach'='ENCROACH'
(Other definitions for encroach that I've seen before include "Intrude on somebody's territory or time" , "Advance beyond proper limit" , "'Trespass, infringe (8)'" , "Advance gradually (beyond expected limits)" , "Impinge, infringe" .)