according you theory average waiting time should be ~7 day, but I got reward after 13 day for first, and for second input of 141clam already 10day without reward.
Yes, the key word here is 'average'. Each stake can take more or less time to actually happen; it's pretty much random, since whether you stake or not is based on the size of the hash of a bunch of stuff.
maybe you have information about clam wallet in yobit exchange ?
I don't, sorry. I personally only really use poloniex if I want to buy or sell CLAMs. It's the biggest market, usually has a decently narrow spread, reasonably low fees, and I have never had problems trusting them with up to 50 BTC or so in my balance. I did play about with one of the other exchanges when they first added CLAM but I didn't like the site felt, or the lack of liquidity in its market so I went back to poloniex.
I can also recommend arranging direct trades in the just-dice chat tab. You can usually find somebody willing to trade CLAM for BTC, and there's a free built in automated escrow system (type /escrow there for details).