I wanted to remove the shadow from one of my JPG pics and I am not able to do so due to this error:
"Could Not Use Clone Stamp Tool Because Area To Clone Has Not Been Defined".
My PS CC version 2017.1.1 on windows.
With the Clone Stamp tool selected, first Alt click (Option click on Mac) on the pixels you want to use to remove the shadow. Then release the mouse and the Alt/Option key and start stamping on the shadow. The pixels you Alt/Option clicked on will be copied to the shadow area.