One Button Layer Clipping
Clipping an adjustment layer to affect only the layer below it required remembering to hold down the Option (PC: Alt) key, while hovering the cursor between the layers, until a black-over-white-circle icon appears, and then click. Now all we have to do is highlight the adjustment layer in the Layers panel and then click the third icon from the left at the bottom of the Adjustments panel (Window>Adjustments). Hooray! No more arcane keystroke/mouse moves!!!