Element - argon - on a sauce (9)
I believe the answer is:
carbonara
'sauce' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'element argon on a' is the wordplay.
'element' becomes 'carbon' (carbon is a kind of element).
'argon' becomes 'Ar' (Ar is the chemical symbol for argon).
'on' means one lot of letters go next to another.
'carbon'+'ar'+'a'='CARBONARA'
Can you help me to learn more?
(Another definition for carbonara that I've seen is " Type of pasta sauce".)