There are some short China, but not one for specifically Chinese real estate.
I believe it's YXI off the top of my head, that's the short China. The biggest holdings are in the financials.
Just remember that China is very much not a free country. It's hard to bet on what will happen to the down side, because the government can pretty much do as they like. And in China, you can't go bankrupt. You pay, or you go to prison.