Checking clearances means making sure you’re not inadvertently referring to real people and real companies in your project.
Rights and Copyright
You can’t copyright titles
Copyright is a bundle of protections granted to the creator of a work. It doesn’t cover the pure idea (“Save the Last Dance with dinosaurs”); it covers the expression of the idea (your original, 120-page screenplay Dinosalsa: The Jurassic Dance).
Surviving the director’s rewrite
There is no grand tradition of a “director’s pass.” When it happens, it’s because some directors (1) believe they can write and (2) believe they can fix the perceived problems in the script. They may say they want to “make it their own.” But underlying that is the fact that there’s something about the script that bugs them, and you haven’t been willing or able to address it.
No one stole your idea
I have very little patience for accusations that someone “stole my idea for a movie.” Or a TV show. But such complaints are common. Sometimes, it becomes a copyright lawsuit. More often, it’s a campaign of whispers.