Old-fashioned spies set up meeting with chief (7)
I believe the answer is:
archaic
'old-fashioned' is the definition.
(I've seen this in another clue)
'spies set up meeting with chief' is the wordplay.
'spies' becomes 'CIA' (Central Intelligence Agency).
'set up' shows that the letters should be reversed in order (in a down clue, letters go up).
'meeting with' means one lot of letters go next to another.
'chief' becomes 'arch' (synonyms).
'cia' backwards is 'aic'.
'aic' put after 'arch' is 'ARCHAIC'.
(Other definitions for archaic that I've seen before include "From the past" , "Ancient, no longer current" , "Primitive" , "Behind the times" , "Belonging to former times like some words" .)