To crop only one layer in Photoshop, you can follow these steps:
1. Open Photoshop and open the document with the layer you want to crop.
2. In the Layers panel, select the layer you want to crop. If the layer is not already unlocked, click the padlock icon to unlock it.
3. Select the "Crop Tool" from the toolbar on the left side of the screen. It's the icon that looks like a rectangle with a grid inside it.
4. Click and drag the Crop Tool to create a crop boundary around the layer you want to crop. This will create a bounding box that defines the area to be cropped.
5. Once you have created the crop boundary, adjust it as desired to include only the part of the layer you want to keep.
6. Press "Enter" or "Return" on your keyboard to apply the crop. This will crop only the selected layer to the area defined by the crop boundary.
7. If you need to make further adjustments, you can use the "Move Tool" and other tools to reposition and edit the cropped layer as needed.
That's it! With these steps, you should be able to crop only one layer in Photoshop.