What is the relationship between angle of attack and wake turbulence?
It is not the angle of attack - downwash intensity grows with lift squared and inversely to the squares of wingspan and speed. Please read this answer on how wake turbulence forms. Now let's look at the parameters you listed:


Heavy: Yes, the heavier the aircraft, the more lift needs to be created. Induced drag grows with the square of lift.
Clean: Not really. With or without flaps the amount of lift is the same. Only the lift distribution over span might be different, but this does not make much of a difference for the wake.
Slow: Absolutely! Induced drag is proportional to the inverse of speed squared.


What is missing from the list is wing span which lets induced drag grow with the inverse of its square. The angle of attack is only indirectly responsible for induced drag because lift is (within limits) proportional to the angle of attack.