How to make layer effect but only to part of the edge?

I want to make something that look like layer effect, but I only want the effect to be on part of the edge, not the whole edge, like this:

can you use a mask?

Double-click on the layer icon, and check the layer masks hides effect box. Then add a layer mask and brush out the object. This will only work as you have the object (I.e., the same color as the bg). Otherwise you need to duplicate the object, one with a 0% fill on top for the effect (and layer mask) and another version below.

J

Without a mask:

In the layer effect dialog box, reduce the shadow opacity to 0%, or set its mode to screen or lighten.

Yarp.