Gold and glass walls in a French city (7)
I believe the answer is:
orleans
'french city' is the definition.
(I've seen this before)
'gold and glass walls in a' is the wordplay.
'gold' becomes 'or' ('or' is the heraldic name for gold).
'and' means one lot of letters go next to another.
'glass' becomes 'lens' (I've seen this in another clue).
'walls in' is an insertion indicator (inserted letters are walled in).
'lens' going around 'a' is 'leans'.
'or'+'leans'='ORLEANS'
(Other definitions for orleans that I've seen before include "City where Joan of Arc is said to have raised the English siege" , "historic French city" , "French city saved by Joan of Arc" , "Joan of Arc was known as the Maid of . . . . . . ." , "Fabric" .)