Fake news is when a media outlet invents a story or deliberately releases a story with false information to motivate it’s viewers or reader’s, traffics in it as does the FOX TV network - the National Enquirer - Breitbart and so on.
News outlets that traffics in baloney like calling into question Obama’s birth certificate when it’s known his birth place and views it as news worthy that’s Fake new - Reporting Donald Trump lying he has people working in Hawaii on his birth info that can’t believe what they are finding isn’t fake news it’s Just reporting that an idiot is lying. That’s actually news. When news outlets use that as a.basis for calling into question Obama’s birth place then that becomes Fake News.
Retracting at passage or correcting one does not make news fake.