Subject of French writer approaching depression (9)
I believe the answer is:
dependent
'subject' is the definition.
('dependent' can be a synonym of 'subject')
'of french writer approaching depression' is the wordplay.
'of french' becomes 'de'.
'writer' becomes 'pen' (I've seen this before).
'approaching' says to put letters next to each other.
'depression' becomes 'dent' ('dent' can be a synonym of 'depression'**).
'de'+'pen'+'dent'='DEPENDENT'
(Other definitions for dependent that I've seen before include "Relying/contingent (on)" , "Subject" , "Reliant" .)