Clark actually bowled pretty well today aside from the death overs IMO. I think he'd probably be a better ODI bowler if he got the chance to bowl with the new ball, but it's unlikely he's going to any time in the near future, even after McGrath retires, given that Lee and Bracken take it most games. I don't think he's incapable of bowling well in the format, but he's probably pretty close to losing his place at the moment. Lee, Bracken, McGrath and Hogg are all certain to make the WC squad, so that leaves two spots for Johnson, Clark and Tait to share. If Tait gets another run in New Zealand, he may have a chance to move ahead.
The one thing Clark has in his favour is that the Australian selectors favour having players in common across the two formats. Given that Clark and Lee will be the spearheads of the test attack in the forseeable future, Clark will get plenty of chances to cement his spot in the ODI team.