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