Land is divided into fiefs. Fiefs are headed by lords and knights. Only those who are part of fiefs are able to farm limited renewal resources on those fiefs, and they are called villeins. Burgesses are subjects of the Duchy of Wessex, but they are free men. They are not part of a fief, they are part of a boroughs, a town. This is why they are called burgesses and not enfeoffed villeins. But buildings in towns are limited, and the burgesses sacrifices his ability to legally farm from his lord's fief.
If you want to think of fiefs as subclans, I suppose you can. Sleggjaholl is a fief and it certainly is a subclan. But everyone here is a member of the Duchy of Wessex.
I don't know how taxes will work exactly in Darkfall. Some say they can be withdrawn automatically. We will apply what works, and in percentages which we discover to be reasonable.