Crossing a bird (7)
I believe the answer is:
pelican
This clue is a double definition.
'crossing' is the first definition.
(pelican crossing is a type of road crossing)
'a bird' is the second definition.
(pelican is a kind of bird)
(Other definitions for pelican that I've seen before include "Large-billed waterbird" , "Long-billed waterbird" , "Aquatic bird with pouch" , "Seabird having a large bill with a pouch for fish" , "Large-pouched bird" .)