Here is the full list of all 14 Worms Clan Wars achievements.
Defeat the evil Lord Mesmer
Kill a total of 300 enemy worms
Complete "Fugu Fountain"
Complete "The Class Act"
Complete a multiplayer match using your personally created landscape
Win a ranked Clan Match
Complete "Worm On Trap"
Kill a total of 100 enemy worms
Create your own clan, complete with emblem
Complete all Worm Ops missions
Fully customise your worms
Complete "Meat In The Middle"
Complete "The Mission Before Time"
Kill a total of 10 enemy worms