Avian interest (5)
I believe the answer is:
hobby
This clue is a double definition.
'avian' is the first definition.
(hobby is a type of bird - avian means bird)
'interest' is the second definition.
(I know that hobby is a type of interest)
(Other definitions for hobby that I've seen before include "Small falcon" , "pursuit of birdwatcher?" , "Bird - eg bird-watching" , "activity giving pleasure" , "interest" .)