Clan Inventory and Defense Button
The little things slip through the cracks. As town halls are upgraded, we get new walls, new bombs, new traps and new resources. All of which have come along well after the clan is packed with higher level items. Rather then hunting and clicking on every single piece of the clan I would love to see an inventory list. All of the different items grouped together and have the ability to upgrade them right there in the list. That way you can easily see what needs to be brought up to speed. Maybe the ability to click on an item in the list and it's location on the clan map be highlighted.
Also, a defense button or mode. Something simple that shows you all of the defensive coverage across your clan. That way you can easily see your weak spots and aren't clicking on each and every single defensive structure when placing or rearranging items.