Long-term convict (5)
I believe the answer is:
lifer
'long-term convict' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for lifer that I've seen before include "One behind bars for ever" , "Long-term prisoner" , "One given lots of porridge" , "Rifle (anag.)" , "One with maximum sentence" .)