China does not need to clarify anything. Nine Dash line is Nine Dash line, it is as simple as that. The fault lies with those who deliberately add skewed interpretations to the Nine Dash Line, such as calling the line a claim on international water.
As long as China refuses to clarify the 9-dash line, then her Asia and Pacific neighbors will use it against China. If China doesn't care (as she clearly doesn't), then bully for China.
This has nothing to do with US's skewed view of innocent passage. Again, the keyword here is innocent passage. Spying and other military activities against China are not equivalent to innocent passage.
The US view parallels most of the world and it's China who's different. If China doesn't care what the rest of the world thinks (and she doesn't), then bully for China. But since China has conducted spying missions in other nations' EEZ, then it's hard for China to play it both ways. But if China could muscle her way into it, then bully for the Middle Kingdom.
China's view with regard to military activities on international water is the same as most of the world. By saying China cannot do X, it is the US who is trying to regulate foreign military activities in international water.
Saying a lie over and over doesn't make it true. Let's do this one more time: US and most other nations believe EEZ outside 12 mile limit is international water (eh, this means you could spy in it), and China feels she could spy in other nations' EEZ (Hawaii and Guam), but no one else could spy in her EEZ. But if China could browbeat others to allow her to have her cake and eat it too, bully for China.