Oliver's requests for more? (6)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

Not 100% sure about this – aside from the protagonist of the Dickens novel, I’m guessing this refers to requests to the dealer in poker for more cards. Or, as Hovis and Simon S point out below, pontoon/vingt-et-un, which we used to play a lot as kids but which had slipped my mind till now