A French writer is newspaper boss? That’s not permitted (12)
I believe the answer is:
unauthorised
'not permitted' is the definition.
('not permitted'->'unauthorized' is in my internal thesaurus and 'ize'->'ise')
'a french writer is newspaper boss?' is the wordplay.
'a french' becomes 'un' ('a' in French).
'writer' becomes 'author' (synonyms).
'newspaper boss?' becomes 'ed' (short for editor).
'un'+'author'+'is'+'ed'='UNAUTHORISED'
'that's' acts as a link.
(Other definitions for unauthorised that I've seen before include "Not officially allowed" , "pirated" , "Illegal - audio hunters (anag)" , "not sanctioned" , "lacking official status" .)