Arctic __: bird that flies between poles (4)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
tern
(Other definitions for tern that I've seen before include "Three-masted schooner" , "Gull-like seabird" , "Fork-tailed seabird" , "Rent out this gull" , "Rent out the bird" .)