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