Clan War Assigned Attacks
I have not seen anything like this in the search but it seemed like an easy idea to implement. Very simple, make it so clan leader/co-leader can put descriptions on the opposing team, this would eliminate the need to use apps outside of the game to assign attacks. Because a normal clan of people who play occasionally, will probably not scroll through all of the chat to see who they should attack. So the description could be about 50-75 characters long, you could put your clan members assigned number in the enemies description. You could also add comments like "Watch for huts in corners," etc.
There could also possibly be a new rank equal to co-leader called "General" or something of the sort. If not that, then possibly a toggle that only the leader could control that allows/unallows that certain clan member to edit enemy descriptions.