I made a quick research in questions tagged crop and 53 from 57 were about clipping/cropping either raster or vector data. Just like clip.
While in the GIS world (i.e., outside GIS SE) 'clip' and 'crop' can have distinct meanings (for example, the ones commented by PolyGeo), within GIS SE tags can be (are) used in a more relaxed terms so to group questions per subject efficiently.
By doing this quick search on crop I saw many potential duplicate questions to clip. Making one tag synonym of the other will help people finding and marking those accordingly. Therefore, I propose clip to be the master because it has been spontaneously used more frequently.
About agricultural 'crops' (the other 4 questions among 57) I think they could be tagged agriculture and we would not have a tag with a competing name from a specific field (agriculture) to a common geoprocessing operation.