Attack Clan Members with No-risk/no-reward sparring matches.
I think it would be fun to be able to attack friends within your Clan in order to test your defenses/offense and see who is truly the best tactician in your Clan.
Select a clan-mate and attack their base at no cost to you or the person attacked.At the start of the battle have the maximum amount of each troops you've unlocked available to you (based on army camp capacity). Then as you plant troops subtract that troops value from the available units left to attack.
It should be limited to people within your clan as you don't want to be able to invade strangers and other clans revealing traps and other strategies. Within the clan you can see all that anyway, so what's to lose?!