Could be a dry ball joint or Caster camber plate bearing
1) Try jacking up the front end with both front tires off the ground.
2) Get under the car with a pry bar of some sort and check for movement between the Spindle and A-arm. making sure not to damage the grease boot, there should be no up/down slack there.
3) Inspect ball joint grease boot for damage/cracks/leaking grease.
4) Have buddy turn wheel left/right while your under car to narrow/verify results.
It could be the joint just recently ran out of grease, then the up/down slack would not be as pronounced, but will get worse over time.
If you have after market CC plates the bearing should be accessable from engine bay for inspection.
Hope this helps.