Audibly talk of argon (3)
I believe the answer is:
gas
This might be a double definition.
'audibly talk' is the first definition.
'gas' can be an answer for 'talk' (gas can mean to chat). I'm not sure about the 'audibly' bit.
'argon' is the second definition.
(thesaurus)
'of' acts as a link.
Can you help me to learn more?
(Other definitions for gas that I've seen before include "Something that is neither solid not liquid" , "Eg, hydrogen" , "Hydrogen possibly" , "that may quickly be stepped on" , "Hydrogen or methane, say" .)