Hint about one fault in French cooking (7)
I believe the answer is:
cuisine
'french cooking' is the definition.
(I've seen this before)
'hint about one fault' is the wordplay.
'hint' becomes 'cue' (I've seen this before).
'about' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'fault' becomes 'sin' (I've seen this in another clue).
'i'+'sin'='isin'
'cue' placed around 'isin' is 'CUISINE'.
'in' acts as a link.
(Other definitions for cuisine that I've seen before include "Culinary art" , "The food" , "Style of cookery" , "It can be French, Italian or Spanish in a restaurant and tasty" , "(French) cookery" .)