Visionary camp inmate I fed to fish (7)
I believe the answer is:
ezekiel
'visionary' is the definition.
(Biblical figure)
'camp inmate i fed to fish' is the wordplay.
'camp inmate' becomes 'zek' (historical term for a USSR prison camp inmate).
'fed to' indicates putting letters inside.
'fish' becomes 'eel' (eel is a kind of fish**).
'zek'+'i'='zeki'
'zeki' going into 'eel' is 'EZEKIEL'.
(Other definitions for ezekiel that I've seen before include "Eponymous OT prophet" , "Hebrew prophet" , "Babylon-exile prophet" , "Good book" , "Biblical prophet" .)