Little the outlaw does for his royal enemy? (4)
I believe the answer is:
john
'little the outlaw' is the definition.
(Little John, friend of Robin Hood)
I don't understand the remainder of the clue.
(Other definitions for john that I've seen before include "With nineteen accross twentieth century US actor known for westerns, etc" , "Wayne, Denver or Elton?" , "where Jack came from" , "Gospel writer" , "Trick" .)