Reportedly expensive source of venison (4)
I believe the answer is:
deer
'source of venison' is the definition.
(I've seen this before)
'reportedly expensive' is the wordplay.
'reportedly' shows a homophone (sound like).
'expensive' becomes 'dear' (I've seen this before).
'dear' is a homophone of 'DEER'.
(Other definitions for deer that I've seen before include "The - Hunter, 1978 film" , "Source of venison" , "maybe does" , "Antler-bearing animal" , "Antlered mammal" .)