Probably not. Clickbank says any product you sell has to be immediately accessible the moment they purchase. An SEO service provides a lot of liability to them.
That said, I think if you have a proven Clickbank account you'll probably have some leeway. There was someone who promoted a coaching program on Clickbank that was basically a promise that he'll teach you stuff. A membership program that gave people access to him. IMO Clickbank probably wouldn't let that fly for most vendors, but this guy had done over seven figures with Clickbank already.
Clickbank's big concern with this kind of stuff is that you won't deliver on your promises and they get stuck with a bunch of chargebacks and refunds. If you have a history you might be able to finesse your way through the system, but for most people the answer is "no."
