The pads of type Custom Shape have the clearance around all the shape. Violations are caught by DRC. (This all, of course, in daily builds.)
This is how a custom shaped (polygon) pad can be created:
1. Create a filled polygon on other than copper layer.
2. In its Properties change the layer to a copper layer.
3. Still in Properties, change one of the points to other than 0 (don't ask me what they are and why, you can try with all zeros...).
4. OK. Accept.
5. It's on a copper layer. Select it and in the context menu select Create Pad from Selected Shapes.
6. Open Properties of the created pad. Open the Custom Shape Primitives tab.
7. Select the polygon and click the Edit Primitive button.
8. Change outline thickness to 0. Accept.
However, I don't know if it's possible to create or use closed shapes with arcs.