Throw, holding an ace in card game (7)
I believe the answer is:
canasta
'card game' is the definition.
(canasta is a kind of card game)
'throw holding an ace' is the wordplay.
'throw' becomes 'cast' (synonyms).
'holding' means one lot of letters goes inside another.
'ace' becomes 'a' (abbreviation).
'cast' placed around 'an' is 'canast'.
'canast'+'a'='CANASTA'
'in' is the link.
(Other definitions for canasta that I've seen before include "Decorated with artificial jewels" , "Rummy-like card-game" , "Two-pack card game" , "Card game of the rummy family" , "Card game like rummy" .)