Diving seabirds
I believe the answer is:
auks
'diving seabirds' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for auks that I've seen before include "Sticky diving seabirds" , "Northern black and white diving birds" , "Stocky diving birds" , "Birds (such as razorbills)" , "Fliers" .)