Nothing specific can be said from the context and only one thing came up in my google search. I know it's a name, and it's probably Arabic in origin. But it just doesn't add up to the story really. It's in the last sentence of the following paragraph:

"You doctors," continued Levinson, "spend your efforts treating symptoms instead of causes. Because I am tired, I must go somewhere and rest; because I can't sleep, I must get out somewhere and exercise; because I have no appetite, I must go away from my business! Why don't you find why I am tired, and can't sleep or eat? I should run my business like that and in a year I'd be broke—machullah!"

I only found it on a thread about favorite words (not poker related words) in a poker forum:

"I've always heard it pronounced gunef or even ganef and in my experience it's meaning is more angle-shooter than out and out crook although I have certainly heard it used in the context of a guy who's business went "machullah" or busto and had all of his property in his wife's name."

So I guess it's something about bankruptcy?

I'm translating this story and really need to know its exact meaning and what language it is from. Thanks!