That would not be a Crop. Cropping changes the document's rectangle canvas size. In this case delete should clear the selected area in the targeted layer when the layer is a normal raster layer. You may see the area turn to a transparency checker board. There can be many reasons you will not see the image area turn transparent. Clear may not be a valid operation. If the layer is not a raster layer. There may be other layer that have pixels in the cleared selection area. Check the Layers Palettes layer 's content thumbnail. What kind of layer is targeted what does it thumbnail content look like is the selected area cleared.