I had a few questions about the clip tool – as it’s a little bit of a pain in inkscape and not the easiest to handle in Adobe Illustrator either.
I use clipping masks a lot as you can create shading and patterns inside objects qucikly and still keep the shapes – while a path intersection destroys the base shapes.
I made this set of tutorials for Inkscape, Adobe Illustrator and CorelDraw. I prefer the ease of CorelDraw over the other two – with Inkscape lacking some key features to make working with an essential tool like clip masks easy on the user.
Let’s take if from the simple shaded ball to something more complex (e.g. a cartoony plane I just did for another tutorial). In order to do the shading on the body (the darker blue part at the bottom of the plane) or the white stripes, you have to create intersecting shapes to cut the white stripes or the lighter body to match the base shape. 
It’s a lot quicker and easier to create the clip mask and ‘throw’ a shape in there – even more so when the shapes get more complex (e.g. a floral pattern on wallpaper) – and it allows you to ‘undo’ the action and release the clip again.

Doing clips inside clips is not possible in inkscape as far as I know [but I might be wrong]. In order to work around that problem try and use the Path/ Intersection tool to create a shape matching inside a base object. 

Once you have created a clipart you can work with the objects inside the clip art just like any other object in Illustrator (e.g. arrange to bring them to the front or send them back inside the stack of objects in your clipping mask).

Even though things might be a little easier to achieve in the other programs Inkscape allows you to achieve the same results with a little bit of patience and trial and error.

Good luck and enjoy your vector bending.

The toolbar of CorelDraw and Illustrator might have changed slightly as I am not up to date on either program. I am still using CorelDraw14 and Illustrator CS.