I'm not sure I understand exactly what you mean by "cropping". However, it should work where crop one clip. Then right clip on it and select "Copy". Then select all the other clips, right click and select "Paste Effects and Adjustments". It will paste ALL of the adjustments on the copied clip. So, if you've done any other "adjusting" to a clip it will paste them all. You may have to temporarily put an extra clip in the timeline with no adjustments, do the cropping, copying, pasting and then remove the extra clip.