its not clamped to anything.
The hose just slips over a tube at the top, and on the bottom it goes into this rubber drain gromitt......

....so you might be able to acess it from under the dash.
These drains are put in pre paint so they are burried and are not easy to install, they go inside the pillars.
Also sounds like your sun roof gasket(around the perimeter) is leaking, you can buy a replacement from the stealership for around $100.
Hope that helps.