Scoop up an enemy with the Wheeldozer.

You can find the Wheeldozer at the Mutant Bash TV location in the Sekreto Wetlands area to the very West of the map. Head to the front door and then turn right and follow the path to find the Wheeldozer parked up.

Get into it and then go and find some enemies. Once you have found some, you need to lower the bucket with 'LB' and then slowly drive into an enemy to have the bucket go under their feet. Then press and hold 'LB' again to raise the bucket with the enemy inside, unlocking the achievement.