Form of rummy (7)
I believe the answer is:
canasta
'form of rummy' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for canasta that I've seen before include "this needs two packs" , "Game played with two packs of cards and jokers" , "Two-pack card game" , "Card-game played with two packs of cards" , "Rummy-like card-game" .)