Clay soil is a massive topic, I suggest you read a few articles - here is a very positive one: https://www.provenwinners.com/learn/dirt-dirt-clay -- like the article states your soil is probably loaded with nutrition, water is the real issue; the way clay soil gets water logged and heavy. The standard rule of thumb with clay soil is: load it up with organic matter (manure, leaves, kitchen compost, etc.). You can just LAYER these on the soil. Additionally, choosing plants that tolerate/like clay soil -- I think the hardy kiwi can tolerate this soil as well as American Persimmon, osage oranges and lots of other plants. They have online plant finders that can help you isolate which plants have the highest probability of success. One thing I did notice when working with heavy clay soils was that plants take a lot longer to establish and grow. I suspect I wouldn't make the effort to plant anything other than plants that are specifically listed as clay tolerant -- you have to go right down to the type of plant: for example: OSAGE oranges not just any oranges .... but maybe all oranges can tolerate clay... you need to check by the type.

- Celeste Archer