head to head battles in a tourney format that gives the winner big prizes at the end. Depending on the size you could have multiple winners with varying payouts. Each person would need to post an entry fee, maybe a combo or elixir and gold or use gems. Different tourneys for different levels and for different payouts. Could even do private tourneys for some inter clan battles in case you wanted to take your elders down a notch.
Each matchup would have a day to conduct a battle against eachother. Scoring of each attack and maybe each defense would determine the winner. Scoring should probably be based a multiple factors.
A couple ideas for scoring : % destruction/defended, loot gained/kept (everyone would have the same to start), initial investment (how much did you spend on troops), how long did battle take, etc (meaning please suggest some if you like the idea). Some of these should be treated as tie breakers while others are main scoring categories. Tourney could last days and you could even do feeder tourneys if it got big enough.