I love the dynamics of that scene.

While it's obviously the first time we see a hint of what Vito would become, you also see the differences between Tessio and Clemenza, and that Tessio was always smarter.

Tessio is the first one to mention the idea of not paying Fanucci.

Clemenza isn't inclined to listen to Vito at all, and tries to dominate the conversation with his ideas, while (other than saying that someone else must be collecting for Maranzalla) Tessio says nothing at all.

He clearly is considering what Vito has to say, and immediately agrees once the plan is laid out.

Clemenza pouts and then reluctantly toasts, either upset that he's being usurped or lacking the vision to see that Vito has the intelligence and force of will to make his plan work.