Yea, there are a few ways to get it out:
1) do what Scott said: drill it out. First you should apply some WD-40 or some sort of oil (engine oil does fine too) and let the oil set in to the cracks between the bolt and the clamp threads and the socket part where the head of the bolt is. If it's a standard 6mm bolt, then use a 3-3.5mm drillbit and drill it it from the reverse end (do not drill the side of the bolt that has the insert, but the tip of the bolt itself), and once the drill locks into the bolt, the bolt should spin out. Sometimes drilling on the right side using
these screw extractor drillbits can fix the problem aswell.
2) If the bolt sticks out from the otherside, you can use an angle grinder to make a little notch into the bolt and use a flathead screwdriver to screw it out the correct way. Do that only if the bolt sticks out a fair amount, otherwise when the end of the bolt reaches the clamp and you're unable to continue to screw your bolt out, you should be able to grab the head of the bolt with nosepliers on the right side. If the bolt isn't longenough, use a hacksaw or angle grinder to snap the bolt in half through the clamp: the right side piece should fall out by default and the left threaded side can be unscrewed out from the left side.
Let me know if one of these methods succeeded or not.