This is a fairly simple suggestion in itself, although maybe a little more complicated to actually implement, but we'll see what everyone thinks I guess.
Quite simply, I'm suggesting that the clan treasury be withdrawable. The way I suggest this is as follows:
Anyone can deposit anything. Leader & co-leaders can withdraw/send items to members from the clan treasury.
This way, clan members can help each other out with credits, gold, mithril & resources etc, without having to run the risk of using the markets and being sniped. This is also a good way for clan members to offer each other "discounts" for their goods and things such as that.
A fairly simple suggestion but one that I think would enhance the trading side of things a fair bit.
I've seen this in other games, the biggest problem was people scamming the clan once they had officer or leader privaleges by using it as thier own personal piggy bank. Admins spent alot of thier time resolving disputes like "I only loaned that gold to the clan now I'm leaving I want it back!". Clan donations should be purely for the clan, noone should have access to those funds.
Then the simple solution for that is you only allow the leader to give things from the treasury, and not any co-leaders. It's a function/feature that would quite frankly vastly improve clan gameplay, and the assumption that someone "might" abuse it shouldn't prevent this from being strongly considered.