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