It may be more interesting looking now! I guess it depends how big it is but if you got it from a nursery I suppose it is big enough to handle this.. I get smaller plants with mail order and they usually survive when their top gets destroyed somehow, in fact they become more bushy. You should seal the cut with something though.. By the way a friend of mine has a pear tree in her balcony with a large branch she accidentally broke and she put it back in place (I suspect most of it was attached) and she sort of bandaided it and the branch continues to grow, I think if it heals it will have a big bump there! I don't know if in your case it could work it depends on how much it separated probably..I suspect the top is important in some shapes of trees but other than stunt its growth a little bit I don't think a cananga would suffer greatly, and I think it could develop another upward growing main trunk under the cut like most of mine do..

It will survive. You better seal it like Fenius said with some glue or bandaid.

I had my champaca in pot for three years. I put in the ground in wrong spot. It got sunburn in the summer and well exposed to freeze in winter spot. Top of the tree started showing dying signs. We put it back in pot, cut the main branch little by little.No new leaves coming out, as most of the main branch is burned with very little green part left on the branch.

Finally we applied fevicol (similar to elmers here) glue at the tip after last cut. Within one month, we have two branches sprouting from spots where there are green on the branch.
Mine survived, so yours will surly.