Question about ::after pseudo element and clippath

Is it possible to create an after element that contains a clippath?

What I am trying isn't working, and I can't seem to find any examples where a clippath is used to create the content for the visual part of the after element.

Basically, I am creating a gannt chart where the boxes of the actions in the timeline have an arrow leading to the next step in the process. So, if what I am trying isn't possible but you have an alternative suggestion, then I would welcome your input.

Thanks.