There are living dinosaurs. They have wings and most of them can fly.

Cloning a dinosaur poses exactly the same challenges as cloning any other animal, and cloning an extinct dinosaur poses the same challenges as cloning any other long-extinct animal. Birds are living dinosaurs and have (of course) dinosaur DNA. Crocodiles are the closest living relatives of dinosaurs that *aren't* birds, so we can do comparisons between the DNA and other biology of birds and crocodiles to get a better idea of what some of the extinct dinosaurs were like, but this only goes so far. The reason is because many dinosaurs, for example Triceratops and most of the rest of the large, plant-eating dinosaurs, went extinct without any living descendents, and yet had millions of years of evolution that led to them since their last common ancestor with anything that's alive now. Just think: the amount of time between Triceratops and Stegasaurus, both of which were of the group of dinosaurs that did not lead to birds, is about 80 million years (Stegasaurus lived about 145 million years ago and Triceratops lived 65 million years ago). This means that there is more time separating these two dinosaurs than there is separating Triceratops from humans!

What would happen if we suddenly found, say, a living descendent of Triceratops? It would answer a lot of questions, and pose a whole lot more (as scientific discovery always does). I doubt we'd be able to recreate a living Triceratops from it, though, for the same reason why we can't recreate a living Tyranosaurus from living birds, and Tyranosaurus does belong to the same group of meat-eating dinosaurs that birds evolved from within. There's just been too much evolution in that time.