Where koala may be in a bit of bother? (2,1,3,4)
I believe the answer is:
up a gum tree
I believe this clue is a double definition.
'where koala may be' is the first definition.
(I've seen this before)
'in a bit of bother?' is the second definition.
(Other definitions for up a gum tree that I've seen before include "In a difficult situation" , "in trouble" , "In a sticky situation" , "In a tight spot (like a koala?)" , "Where koala may be" .)