Milne hopper (3)
I believe the answer is:
roo
'milne hopper' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for roo that I've seen before include "young skipper" , "Marsupial (abbrev.)" , "Diminutive inhabitant of Hundred Acre Wood" , "companion of Pooh" , "short jumper" .)