Excellent of French to provide assistant (4)
I believe the answer is:
aide
'assistant' is the definition.
(aide is a kind of assistant)
'excellent of french' is the wordplay.
'excellent' becomes 'ai'.
'of french' becomes 'de'.
'ai'+'de'='AIDE'
'to provide' is the link.
(Other definitions for aide that I've seen before include "One to assist" , "Adviser or assistant" , "Military officer acting as assistant" , "a help" , "one helping" .)