Idiot losing pounds — an indefinite number — in card game (5)
I believe the answer is:
poker
'card game' is the definition.
(I know that poker is a type of card game)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for poker that I've seen before include "Jabber" , "Fire prodder; game" , "Card-game" , "Pushy person" , "Gambling card game" .)