I had very heavy clay soil when I first turned my ground over with a tiller before 2000. It was so bad I'd have to stop the tiller every 4-5 ft. to clean the tines-----almost gave up. Before I put the first garden in I added truckloads of organic matter in the form of shredded leaves, grass clippings, spillway sand from the Mississippi River and well composted stable waste. Fast forward about 1 year later my soil was MUCH better.
Clay is a bummer, but it can be made better with some work. Almost anything organic you put in it now will only help. It just depends on how much clay you currently have and how much you amend it as to how long it will take for it to become better garden soil.
Right now I have 3 compost piles going in varying stages to be used as things die out and I replant. If you don't already have a pile started, do so and you will enjoy the end result.
I put stuff in my soil every year I still grow alot of stuff. I'm just trying to achieve better drainage. I grow variety of squash, beets. This year I put the red onion,sweet beets,garlic in a raise box since the slugs and snails don't like those sorta things. All squash plants going in the ground. Green pole/beans will have there own area. Just don't have the space to grow alot of vegs.
I heard applying sand can help with drainage issues. I too have heavy clay soil and have been told it can take awhile to achieve the right balance but to keep going on improving your soil. It's like a work in progress I think . Just saying.
Learning as I go and surprising myself when it all comes together......