Prisoner in house before part of journey (7)
I believe the answer is:
hostage
'prisoner' is the definition.
(someone taken as a prisoner)
'house before part of journey' is the wordplay.
'house' becomes 'ho' (abbreviation for house).
'before' is a charade indicator (letters next to each other).
'part of journey' becomes 'stage' ('stage' is part of 'journey').
'ho'+'stage'='HOSTAGE'
'in' acts as a link.
(Other definitions for hostage that I've seen before include "Captive held for ransom" , "She-goat (anag)" , "One held as security" , "One held for ransom" , "Prisoner held as security" .)