Step 1: Beggining
2. Open Inkscape, if you are not familliar with it, go through the tutorials, this will help you.
3. Draw the first frame of your animation(clock this time). I've drawn it using rectangles with rounded edges, a triangle and a circle, pendulum is made by placing an oval either over another one or a rectangle, selecting both of them and pressing ctrl+ + (Path/Union). By the way, the end of the pendulum is hidden under the lighter . Actually, to do this, you must duplicate the darker inner part of the place where the pendulum is, then select the duplicate and the lighter rectangle and press ctrl+ - (Path/Difference). Then arrange the pieces of the clock by sending them back/Forward to get something like the picture. Then draw a white rectangle without borders on top of the clock, and send it to back of the image. With this rectangle you will control the size of your gif and it's essential!
Step 2: Changing the rotation center of the pendulum
Pictures illustrate before(1) and after(2).