How will u be able to achieve xp?

Wars, Geral posts, Events, QI?

Well wolfe, in this case you're looking just for the bad part.
Maybe, without geral posts... And if the people farm obviously will got ban and it don't will count.

What would the purpose of this addition even be?

Good question.
It has no addition but it'd be quite fun actually to see something like this.
I think to maintain xp, you should win clan events. GM's already give out event points to the winners of clan events, using them for a purpose wouldn't be such a bad idea.

It could add another level of competition and fun to the table.

so dose the mebers get perk or items after the clan will reach a sertain level? or something like that

still i support

clan points are yet to be implemented and will do the same, spice up rivalry a bit, not really needed, typical ranking is enough.

I have plans to make something like this for clans. I doubt I'll have any time for it in the near future.

I don't have much interest in adding a system which ranks clans purely off statistics. However, the stats can be interesting. If I ever do tie them into any ranking system, they wont give nearly as many points as wars and events.