First, create a graduated radial filter, with the check mark in "show selected mask overlay".

Then, click on Brush WITHIN the radial tool and select ERASE that is below all the sliders. Erase areas you don't want affected by the filter.

Third, turn off the overlay mask and adjust sliders for the look you want.

Fourth, for more precise control, use the Range Mask (below the brush size and feather). Turn the overlay mask back on; then choose color or luminance. Reduce feather to 0. Click on the dropper and select the area with the color you want to control; then reduce the density until just the area you wish to change is shown in the mask.

Lastly, turn off the mask overlay and adjust the sliders for the desired affect.

This is a really neat trick for faces when using the round radial filter, especially for exposure, saturation and clarity. Also, if you have multiple faces to adjust, you can right click the filter to copy it, then drag to another face and adjust. This saves having to reinvent the filter for every face.

The attached photo is where I applied this to the sky. Have fun with it.