2011 - regular clunk from front left under firm/heavy braking

Purchased in April 2019 and was solid off the lot. Two weeks ago (140,000 miles) started hearing a regular clunk (once per revolution of the wheel) under firm/heavy braking; nothing discernible under light braking. I can see nothing amiss re: bushes and no loose nuts that I can detect. One rotor has a very slight warp (0.002") but no visible imperfections. I've reviewed other threads on similar topics but can see nothing that compares directly with this. Any ideas welcomed.

 

Pad not moving around?

or ball joints?

 

Thank you for responding.

Neither that I can detect.