What's wrong now?

Hello,

1 - This is the shadow texture from the original package you cloned. Simply select the shadow in S4S and click on : make blank

2 - This is the specular texture from the original package. Same here, simply select the specular in S4S and click on make blank. (The specular defines how the light is reflected on your mesh).

3 - This is a weight or Uv_1 issue. Meshes created with Marvelous designer have more vertices than the ones from the sims and are triangulated from the start. That means that the vertices from the body top and the ones from the top do not align. Because of this they will not move exactly the same when adjusting sliders or simply when moving.

You can test in the game and see if this clipping is still visible when you make the sim slimmer. If not then it's a UV_1 problem and is kinda hard and really tedious to fix.
If it persists when the sim gets slimmer, then it is a weight issue and you can try to fix it by manually modifying the weight of the vertices which become visible (easier modification here is to actually change the weight on the nude body top). This is also tedious to do though -_-
You can check this tutorial explaining how it works and giving you tips.