It's fortified wine that's good for Parisian to drink (7)
I believe the answer is:
bastion
'it's fortified' is the definition.
(a bastion is a fortified area)
'wine that's good for parisian to drink' is the wordplay.
'wine' becomes 'asti' (Italian wine).
'that's good for parisian' becomes 'bon' (French for 'good').
'to drink' is an insertion indicator.
'asti' going inside 'bon' is 'BASTION'.
(Other definitions for bastion that I've seen before include "Projecting part of a fortification" , "Fortified place near hostile territory" , "Obtains (anag.)" , "fortress" , "that's fortified" .)