Keep the lanes clear, and the cats that's all about scrap remain here
On top of this Metropolis

from Jay Z – Can't Knock the Hustle (Remix) Lyrics on Rap Genius

Meaning

Get out the way of the money if you are not trying get rich like my team is, the word “SCRAP” is a misspelling and he was referring to Scratch, which means cash when referenced in the book Pimp, by Robert Beck, Iceberg Slim, who Jay-z also referenced himself as.
So if you about Scratch which is money you stay on top of the world. or Metropolis as he stated.

To help improve the meaning of these lyrics, visit “Can't Knock the Hustle (Remix)” by Jay Z Lyrics and leave a comment on the lyrics box