For most adult cats in most homes, yes, and it is what the majority of cats have used for decades. Three worries get raised, and only one of them, the dust, is something anybody can measure. We measured it, and the answer depends far more on which bag you buy than on the word clay.
This is the real one, and it is the only one of the three anybody can measure at home. Clumping clay is ground fine so it can seal urine, and fine grinding makes dust. How much varies enormously between bags.
Across the clay litters we have weighed, dust per pour ran from 0.03mg on Dr. Elsey's Ultra to 0.58mg on Frisco by Chewy. "Clay" tells you almost nothing on its own; the bag does.
Sodium bentonite swells when it gets wet, and that is the property the whole product is built on. The worry is a kitten or a cat that eats litter off its paws taking in enough for it to matter.
We cannot test this and will not pretend otherwise. It is a question for your vet, and it matters most with young kittens, cats that groom obsessively, and cats known to eat non-food items. Those are the households where a pellet or paper litter is the easier choice.
Bentonite is strip-mined and does not break down. A clay box goes to landfill and stays there. That is an environmental objection rather than a safety one, and it is a fair objection.
If this is your reason for asking, the answer is a plant-based litter rather than a different clay. Corn, wood, walnut, paper and tofu litters all sidestep it.
Same test, same pour, milligrams of airborne particulate. Clay litters on the left of the split, everything else on the right. Notice the overlap: the cleanest clay beats several plant-based litters.
Dust figures are our own weighings on litter we purchased. This page is not veterinary advice, and where a question needs a vet we say so rather than guessing.