From the article:
"According to a source familiar with the contract, Smith's deal (which guarantees him $21 million and could be worth as much as $42 million over six years) includes a weight clause that would allow the Bengals to fine Smith up to half his weekly game check every time he fails to appear on the 45-man active roster and weighs in at 350 pounds or more."

If Andre Smith is as good as he's supposed to be, then this shouldn't really be a problem. Barring injury, he'll be on the roster week in and week out. But if he's a bust, the Bengals might be able to cash in on it, if he also lets his weight go a little bit.

A surprisingly shrewd move by the Bengals. I'm betting he's over 350 pounds right now, so he better start working right away.