Prisoners upset by past vice (8)
I believe the answer is:
captives
'prisoners' is the definition.
('captive' can be a synonym of 'prisoner')
'upset by past vice' is the wordplay.
'upset by' indicates an anagram.
'past'+'vice'='pastvice'
'pastvice' anagrammed gives 'CAPTIVES'.
(Other definitions for captives that I've seen before include "They are held as prisoners" , "Prisoners, hostages" .)