House for men only, originally earmarked for captive (7)
I believe the answer is:
hostage
'for captive' is the definition.
(hostage is a kind of captive)
'house for men only originally earmarked' is the wordplay.
'house' becomes 'ho' (abbreviation for house).
'for men only' becomes 'stag' (as in a stag do).
'originally' indicates taking the first letters.
The first letter of 'earmarked' is 'e'.
'ho'+'stag'+'e'='HOSTAGE'
(Other definitions for hostage that I've seen before include "One held as security" , "Prisoner kept as security" , "One held captive" , "One held for ransom" , "Prisoner held as surety" .)