Confection thats doubly good in Paris (6)
I believe the answer is:
bonbon
'confection' is the definition.
(bonbon is a kind of confection)
'doubly good in paris' is the wordplay.
'doubly' indicates the doubling of some letters.
'good in paris' becomes 'bon' (French for 'good').
'bon' duplicated is 'BONBON'.
'thats' acts as a link.
(Other definitions for bonbon that I've seen before include "Candy, doubly good in France?" , "French sweet" , "Confection" , "Sweetie" , "a tasty sweet - in France" .)