It's not a battery hog list really, just a list of how much battery different apps use. It goes based on the last day or 7 days generally. There's really no good way to clear it aside from perhaps resetting all settings or restoring the phone from new.
Well, the battery usage is over time, so even if/when cleared there wouldn't be any information there for a little while until some data is gathered over at least some hours to show what has been using up the battery over that time (last X hours essentially).