Substance such as laughing gas or rust (5)

I believe the answer is:

oxide

(Other definitions for oxide that I've seen before include "Chemical compound" , "Compound such as rust" , "Eg, rust" , "Compound of oxygen with another element" , "Rust, for instance" .)

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.