I live in zone 7 in Virginia. My garden was all over grown. I just removed the grass. The soil is clay. Is it too late to plant a cover crop? I was thinking of using red clover. Thanks.
No, you can plant into the fall.
Here are some links with more information.
I would also recommend contacting your local County Extension Office and inquire on the best plant cover crops for your region and soil conditions.
I am including a link to locate your nearest office.