One bringing new arrivals by air? (5)
I believe the answer is:
stork
'one bringing new arrivals by air?' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
This is all the clue.
Can you help me to learn more?
(Other definitions for stork that I've seen before include "Mythological baby-bringer" , "Large wading bird" , "Bird that delivers babies?" , "The baby bird, so to speak" , "Long-legged bird" .)