Do drudgery for Dickens (5)
I believe the answer is:
devil
This clue is a double definition.
'do drudgery for' is the first definition.
(devil can mean to act as an assistant)
'dickens' is the second definition.
(Dickens is an old name for the Devil)
(Other definitions for devil that I've seen before include "Imp" , "Wicked person" , "Lucifer" , "Demon" , "Terror" .)