She got her cutie mark when flying for the first time with no help and trusting herself.
Clover Charm is calm, witty and fearless. Clover grew up with an over the top mom who wanted away from the uptight lifestyle of Canterlot so they moved to ponyville. She wants to protect Skipper from herself so she watches over and corrects Skipper.
She got her cutie mark by perfecting her technique of magic and plants. A magical botanist.