Combustible substance (4)

I believe the answer is:

fuel

(Other definitions for fuel that I've seen before include "Power source; inflame" , "Coal or gas?" , "Combustible material" , "Eg, coal or oil" , "coal etc" .)

I've seen this clue in The Sun.

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.