Self explanatory, get 10 kills with your shovel, in a single game.
You can easily get this by creating a game (with bots) with 9 players and a time frame of 10 minutes. You can choose any map as you are using your shovel. Simply, just go around whacking people with your shovel, and before you know it you will have killed 10 people.
Note: It takes 1 shot from behind to kill them, and at least 2 if you the front of them, so sneak up and hit them from behind for some easy kills.