Key French couturier reserving time for press chief (6)
I believe the answer is:
editor
'press chief' is the definition.
(chief of a newspaper)
'key french couturier reserving time' is the wordplay.
'key' becomes 'e' (musical key).
'french couturier' becomes 'dior' (Christian Dior).
'reserving' is an insertion indicator (inserted letters get reserved or contained).
'time' becomes 't' (abbreviation).
'dior' placed around 't' is 'ditor'.
'e'+'ditor'='EDITOR'
'for' is the link.
(Other definitions for editor that I've seen before include "One working on paper" , "Cudlipp, for one" , "Do tire out the newspaper head" , "Newsman" , "Director of newspaper" .)