I know Clint Barton died in the "Avengers Disassembled" story arc, but he's fighting with the New Avengers now as Ronin. How did he come back?
He showed up in "House of M" where he apparently was killed again. Then sometime later he just showed up at the destroyed Avengers Mansion (I think thats how it went down). He then went and found Wanda, slept with her, and left. And then took on the whole Ronin character.
As far as I know its never been explained how he came back. He just did.