Doctor of French has style (4)
I believe the answer is:
mode
'style' is the definition.
('mode' can be a synonym of 'style')
'doctor of french' is the wordplay.
'doctor' becomes 'mo' (medical officer**).
'of french' becomes 'de'.
'mo'+'de'='MODE'
'has' acts as a link.
(Other definitions for mode that I've seen before include "Way, style" , "Manner, style" , "Way of operation" , "Manner of dome" , "Form or style" .)