For the birds? (5)
I believe the answer is:
avian
'for the birds?' is the definition.
(avian means relating to birds)
This is all the clue.
(Other definitions for avian that I've seen before include "Regarding birds" , "Like rails, for example" , "Pertaining to or characteristic of birds" , "To do with birds - like a dangerous flu" , "Relating to birds" .)