it is interesting to note that my base soil here, without any amendments or working over, is very clay based. Its an orangish / brownish clay. The veggie garden took YEARS of amending the top layers with organics, grass clippings, leaves, black soil, sand, etc to make it finally a decent producer. Otherwise lots of runoff, the clay wasn’t absorbent at all. Thats why I even use my compost bin when planting new ornamentals in the yard, the soil is generally shit if it wasn’t located within a planting bed (dig up lawn, its orange clay soil).
But the beds that have 8-12" of nicely amended organic black soil on top of that clay, they do VERY well…