I think the feature of getting notifications when anyone in your clan is being attacked should be implemented in the game. That way, those who can, can hop on and help then from being zeroed.
Form a hive. Pretty easy to see when your clanmembers are being attacked when you are hived. If you see a clan member being hit, you send your clan a message using a third party chat service (or mail everyone in game individually) and presto, you just notified your clan.