Eucalyptus eater (5)
I believe the answer is:
koala
'eucalyptus eater' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for koala that I've seen before include "Aussie tree-climber" , "Australian tree-climbing marsupial with grey fur and big ears" , "Aussie gum-chewer?" , "leaf-eater" , "Arboreal Australian native" .)