Card game accountant rejected at sickbay (7)
I believe the answer is:
canasta
'card game' is the definition.
(canasta is a kind of card game)
'accountant rejected at sickbay' is the wordplay.
'accountant' becomes 'ca' (abbreviation for chartered accountant).
'rejected' says the letters should be written backwards.
'sickbay' becomes 'san' (I've seen this in other clues).
'at'+'san'='atsan'
'atsan' backwards is 'nasta'.
'ca'+'nasta'='CANASTA'
(Other definitions for canasta that I've seen before include "Card-game played with two packs of cards" , "Game played with two packs of cards and jokers" , "Card game of the rummy family" , "Can a staff cook stomach game?" , "Card game at a scan" .)