“I’ve got my own marching band/Guess I lost my give a damn,” snarls Kassi Ashton in her current single “Violins,” rebuffing a clingy ex with cool nonchalance. In the song’s new video, Ashton imagines a high school scene where she’s the baddest drum major in town.

“I wanted something — and this fits well with who I am anyway — something between Gwen Stefani, No Doubt days, like punk, when she had the blue hair with the bun and the rhinestones around her eyebrows, and of course the queen Beyoncé,...