Lucifer (5)
(Other definitions for devil that I've seen before include "Lived with Satan" , "See 11" , "Old Nick, Satan" , "Demon" , "Beelzebub, Satan" .)
'lucifer' is the definition.
(I know that lucifer can be written as Satan)
This is the entire clue.
(Other definitions for satan that I've seen before include "arch-fiend" , "Fiend" , "Old Nick, Lucifer or Beelzebub" , "Prince of Darkness" , "The devil, Beelzebub" .)