Island native, flightless bird, going between both sides (5)
I believe the answer is:
lemur
'island native' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'flightless bird going between both sides' is the wordplay.
I cannot quite see how this works, but
'bird' could be 'emu' (emu is a type of bird) and 'emu' is found within the answer.
'both sides' could be 'lr' (abbreviation for left and right) and 'lr' is located in the leftover letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for lemur that I've seen before include "A primate; sounds like a S. Am. city" , "Monkey-like creature of Madagascar" , "one in the bush?" , "Primate found only in Madagascar" , "Tree-dwelling primate" .)