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.