Crop a path

You can crop a path using the shape of another path. The front or topmost path defines the shape of the cropped area.

1. Select the path object that defines the area you want to crop.

2. Select Modify > Arrange > Bring To Front.

3. Hold down Shift and add to the selection the path object you want to crop.

4. Select Modify > Combine Paths > Crop.

   The resulting path object retains the stroke and fill attributes of the object that is placed farthest back.

 community help (adobe.com)