Thank you for your question. Believe it or not, we get this question quite often. It's a difficult gardening situation and it's hard to find the right answers. I usually refer to the following publication, which is linked below: The Best Plants for 30 Tough Sites by Myer, Brown and Zins from the University of Minnesota. There is a section on Steep Slopes and gives you lists of trees, shrubs, and native grasses for a sloping area. You also have the challenge of clay soil, but there should be some type of plant that will thrive. Best of luck to you and here is the link:

The Best Plants For 30 Tough Sites (umn.edu)