Mostly, Clean Romances in all their subgenres are known not only for being clean in the romance area, but also in regards to violence. It's pretty simple - no violence at all, or if there is some, it implied or extremely light. A quick punch or kick and the curtain closes on the scene.
Now, I have to admit, my books don't always conform to the strictest lines of these guidelines. Not just for the sake of violence, but because the storyline requires the altercations.
A story can't be sweet with violence, it's kind of an oxymoron. But can it still be clean? I'd love to hear your thoughts!