There is a spring clip holding it into a groove on the CV, but hold it with the broken end down and tap the CV joint from the top with a hammer (don't batter it senseless).
Or, broken end down tap it against a big piece of wood to try and shock it out.
It MIGHT come out - but probably not.
I would get a gooood drill bit, get it into the vice or ideally the pillar drill and drill the middle of the shaft - I'd then go about screwing something into it and making a slide hammer arrangement to hoick the broken piece out.
Or, maybe a new CV joint to be honest - by the time you fill the CV with metal it's going to need a jolly good cleaning!