Maybe the clan "diversity" Should be integrate as part of the skill of the clan leader or the clan captains in general. So if the old clan leader dies, the heir assumes and the clan is shaped as his leadership is.
So clan levels will vary on the game.
A bad heir can trigger rebelions for example.
A new clan heir with bad relations to the other clans can trigger expulsion from a kingdom, civil war and the clan should loose a level or 2 if the old warlord dies and is substituted by a new leader that never had his own party...