Almost done! Remove the top of the battery. This is the piece we want. solder a couple of wires on to the back and you have a 9v battery clip.
(I'm guessing you know how to solder but if you don't you may want to look at noahw's exceptional instructable https://www.instructables.com/id/How-to-solder/
This is a very short, very easy instructable, but it is quick way to save $0.25 and the 3 days of shipping.