eucalyptus eaters (6)
I believe the answer is:
koalas
'eucalyptus eaters' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for koalas that I've seen before include "Australian tree-climbing mammals" , "Tree-climbing marsupials in Australia" , "Australian tree-climbing marsupials" , "Tailless Australian marsupials" , "Australian tree-climbing bears" .)