Old-fashioned secretaries not completely prepared (5)
I believe the answer is:
passe
'old-fashioned' is the definition.
(I know that old-fashioned can be written as passe)
'secretaries not completely prepared' is the wordplay.
'secretaries' becomes 'PAs' (personal assistants).
'not completely' means to remove the last letter.
'prepared' becomes 'set' (set up or ready).
'set' with its last letter taken off is 'se'.
'pas'+'se'='PASSE'
(Other definitions for passe that I've seen before include "Out of date" , "Out-of-date (French)" , "-- -partout" , "Master key - picture mounting" , "Outdated" .)