A few things it could be:
1) Lug nuts need to be re-torqued. I know it sounds dumb, because you'd figure you couldn't be so absentminded as to forget to retorque them, but it was what was causing the same clunking for me for a bit. lol
2) Check the stabilizer link nuts, they might also need to be tightened.
3) Could be the shock nut as @
churchx mentioned