Neon or xenon (3)
I believe the answer is:
gas
I believe this is a double definition.
'neon' is the first definition.
(I've seen this in another clue)
'xenon' is the second definition.
(thesaurus)
(Other definitions for gas that I've seen before include "natural resource" , "Hydrogen, for example" , "Domestic fuel" , "In brief, American petrol" , "idle chit-chat" .)