You can group adjustment layers so that only the layer immediately below the adjustment layer is affected. To do this, press and hold the alt key, and move your mouse pointer from the adjustment layer to the layer immediately below. When the mouse pointer turns into two small overlapping circles (over the border between the layers), click your left mouse button.

 

 

Here you can see that the adjustment layer has been grouped with the layer immediately below. It will now affect this layer only. The affected layer has its title underlined, and the adjustment layer has a right angled arrow pointing down to the next layer. This is also known as a clipping group.