Native Australian, this crossword writer's generous (5)
I believe the answer is:
roomy
'generous' is the definition.
(I've seen this before)
'native australian this crossword writer's' is the wordplay.
I cannot quite see how this works, but
'australian' could be 'roo' (short for kangaroo - Australian animal) and 'roo' is present in the answer.
'writer's' could be 'my' (belonging to the person who set the crossword) and 'my' is found in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for roomy that I've seen before include "Commodious" , "Voluminous" , "Having plenty of space" , "Comfortably large" , "With ample space" .)