Inventor discussed French symbol (9)
I believe the answer is:
'inventor' is the definition.
(Christopher Cockerell, inventor of the hovercraft)
'discussed french symbol' is the wordplay.
'discussed' shows a homophone (sound like).
'french symbol' becomes 'cockerel' (roosters and cockerels are symbols of France).
'cockerel' sounds like 'COCKERELL'.
(Another definition for cockerell that I've seen is "Inventor of special craft".)