Talk of neon, say (3)
I believe the answer is:
gas
I believe this is a double definition.
'talk' is the first definition.
(gas can mean to chat)
'neon say' is the second definition.
(neon is a kind of gas)
'of' is the link.
(Other definitions for gas that I've seen before include "State of matter not solid or liquid" , "What's needed to drive" , "idle chit-chat" , "Hydrogen or oxygen, say" , "American fuel" .)