Here is the full list of all 31 Idle Clans achievements.
Join a minigame
Steal from the royal clan
The true test for any respectable chef... Make a pizza.
Purchase the most glamorous property available
Create a godlike item
Grow some watermelons
Reach level 100 in a skill
Smith a piece of Astronomical armour
Perform a leaderboard search
Defeat a boss
Receive a boss key
Equip diamond jewellery
Prepare a special dish
Eat a burger in battle
Battle a monster with an Outstanding weapon
Achieved upon reaching your first million
Enchant an item
Defeat a dragon
Purchase your first property. It's nothing to brag to your parents about, but it's a start.
Refine an item
List an item for sale
Create silver jewellery
Purchase an upgrade
Send an item to your clan's vault
Join a clan
Create a clan
Plunder a small, helpless village
Complete the tutorial
Your first level up
Reach a billion gold
Reach max level in a skill