[Arran]

I've never had much luck on permanently repairing veneer cracked across the grain over a curve like that, especially that long of a crack. Part of the reason it cracked is that the veneer is already under tension where it wraps around that curve and whatever was under it obviously absorbed some moisture, swelled up, and pushed the veneer past it's limits. Wood generally expands and contracts across the grain, not along the grain, so it could not have cracked because of shrinkage. What you can reasonably do about it is another story, it definatley is not the sort of thing for beginners to tackle, it usually involves taking the cabinet apart to a certain extent, removing the old veneer, and then replacing it. It may be easier to find an empty cabinet then to repair that veneer, the good news is that it was a fairly common style.
Regards
Arran