Get discontented prisoner to bury device (7)
I believe the answer is:
printer
'device' is the definition.
(printer is a kind of device)
'get discontented prisoner to bury' is the wordplay.
'get' is a charade indicator (letters next to each other).
'discontented' says to hollow out the word (remove centre letters) (the word's contents are removed).
'to bury' becomes 'inter' (to inter is to put into the ground).
'prisoner' with its centre removed is 'pr'.
'pr' put next to 'inter' is 'PRINTER'.
(Other definitions for printer that I've seen before include "Producer of reading material" , "Compositor" , "Computer attachment to produce paper documents" , "eg Typesetter" , "See 13 Down" .)