How you crop an image in InDesign depends on the image’s makeup. A student asked about cropping off content from the side of a layout. The lesson uses a compound path as the tree shapes were originally text characters. This video shows how to use the Pathfinder Subtract command to crop off the excess image, as well as how to simply crop a placed graphic.
Keep in mind when using Pathfinder that the cropping rectangle (shown in the video with a black stroke for reference) needs to be stacked above the image/path you want to crop.