Crossword Genius

A gas burner! (4)

Ross

I believe the answer is:

coal

I'm a little stuck... Click here to teach me more about this clue!

This might be a double definition.

'a gas' is the first definition.
(thesaurus)

'burner' is the second definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.

Can you help me to learn more?

(Other definitions for coal that I've seen before include "Fossil fuel" , "Char" , "Carbon fuel" , "Carbonaceous rock used as fuel" , "Mined fuel" .)

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