arcgis-pro
This may seem like a simple question, but I cannot seem to just get the part I want from the map layer in the layout tab in ArcGIS pro.
This is a view of what it looks like,
I just want the part where the kernel density layer is plus a part of that basemap.
I try to resize it but then it does not achieve what I want.
To reproduce what you are describing I did the following using ArcGIS Pro 1.4:
I think what you are describing is by design in ArcGIS Pro.
I think what you may be looking for (perhaps submit an ArcGIS Idea) is a new type of Map Frame where the layers are dependent on what is in the Map/Basemap but the visibility settings can be independent.
However for now I think you may need to copy your Map/Basemap and have the separate Map Frames access different Maps/Basemaps.
You need to resize your index frame further. The reason your labels look messy is because it's trying to label features off the side of the frame. If you resize so none of these features are visible, it won't try to label them, and your labels will look much tidier.
Each time you resize your index frame you will need to reset your desired scale for the frame, as ArcGIS Pro seems to like zooming to make the same extent visible rather than keeping the scale the same. There may be an option to keep the scale when resizing, but I haven't been able to find that yet.
Other than that, your process looks fine - when I step through my different pages, the index frame updates to centre on the current page, and the rest of the grids label fine.
Best Answer
If you want to clip/crop the the map to a layer this is a property of the Map DataFrame.
You can use vector or raster layers to clip.As always more information is found in the Help File.