If you can't figure out what the establishment is, the political philosopher Jack Black has a good definition.
"You don't know the man? Oh, well, he's everywhere. In the White House, down the hall," he rants in the movie School of Rock. He adds, "And there used to be a way to stick it to the man. It was called rock 'n' roll."
This idea is at the core of what establishment means in the 2016 presidential race, according to one (actual) political analyst.