Cleaner, very French, where there's a Gothic cathedral (8)
I believe the answer is:
chartres
'where there's a gothic cathedral' is the definition.
(site of Chartres Cathedral)
'cleaner very french' is the wordplay.
'cleaner' becomes 'char' (charwoman is a type of cleaner).
'very french' becomes 'tres' ('very' in French).
'char'+'tres'='CHARTRES'
(Other definitions for chartres that I've seen before include "French city with a cathedral renowned for its stained glass windows" , "Gothic cathedral on R. Eure" , "French town with famous cathedral" , "N French city with a distinctive Gothic cathedral" , "Famous French cathedral city" .)