Most likely culprit is a guide rod mount. If you brake while it is clunking does it go away?
Best way to check as mentioned previous is to jack the tire up(be sure to properly supprt the vehicle) and check for play. Grab the tire at 12 & 6 oclock and try to rock it. Play/noise would indicate ball joints are bad. You should be able to tell if the top or bottom is the problem.
Next grab the tire @ 3 & 9 oclock. Check for play again. This would indicate steering components worn- ie tie rods, idler arm bushing steering shock etc.
To check the guide rod mount I use a pry bar. At its base there is a clamp on the rod. Try to pry it forward. Movement should be minimal. If you get a lot of play(> 1/4") that is the issue.

Good Luck

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