Dross on the surface of liquid (4)

I believe the answer is:

scum

(Other definitions for scum that I've seen before include "Worthless man" , "Impurities that rise to surface of liquid" , "Dross" , "The lowest" , "dirty film" .)

I've seen this clue in The Times.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.