Spies initially all men? (6)
I believe the answer is:
agents
'spies' is the definition.
(secret agents)
'initially all men?' is the wordplay.
'initially' indicates taking the first letters.
'men?' becomes 'gents' (gent is a kind of man).
The first letter of 'all' is 'a'.
'a'+'gents'='AGENTS'
(Other definitions for agents that I've seen before include "Factors" , "They act for actors" , "travelling salesmen" , "They do business on behalf of others" , "They operate on behalf of others" .)