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