Improved demand for card game (9)
I believe the answer is:
newmarket
'card game' is the definition.
(I know that Newmarket is a type of card game)
'improved demand' is the wordplay.
'improved' becomes 'new' (new and improved).
'demand' becomes 'market' (market can mean commercial demand).
'new'+'market'='NEWMARKET'
'for' acts as a link.
(Other definitions for newmarket that I've seen before include "Betting card came" , "course?" , "Racing town" , "Suffolk racecourse" , "Suffolk town" .)