How do we handle this employee’s abrasiveness toward a supervisor?

Q: “Recently we acquired a new supervisor. My issue is that one of our employees is having difficulty responding to this person. She is giving this new supervisor attitude and we normally do not tolerate this. She has been sassy and there are even text messages to prove this. We have a great office culture and do not wish to lose either. What would be the best way to advise said sassy employee?" – Anonymous, Louisiana