Smart guy makes a witticism spoken in French (6)
I believe the answer is:
pundit
'smart guy' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe there's an association between them I don't understand?
'a witticism spoken in french' is the wordplay.
'a witticism' becomes 'pun' (pun is a kind of witticism).
'spoken in french' becomes 'dit' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'pun'+'dit'='PUNDIT'
'makes' acts as a link.
Can you help me to learn more?
(Other definitions for pundit that I've seen before include "Sewing instruments" , "Maestro" , "A person of great learning" , "Expert in a particular field, often consulted" , "Talking expert" .)