Organ generating gas (5)

I believe the answer is:

argon

'gas' is the definition.
(argon is a gas)

'organ generating' is the wordplay.
'generating' indicates an anagram.
'organ' anagrammed gives 'ARGON'.

(Other definitions for argon that I've seen before include "noble element" , "something inert and insubstantial" , "Inert eighteen ac gas" , "Chemical element" , "Gas, 1% of atmosphere" .)

I've seen this clue in The Mirror.

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