Razorbill birds (4)
I believe the answer is:
auks
'razorbill birds' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for auks that I've seen before include "Northern black and white diving birds" , "Sticky diving seabirds" , "Fliers" , "Birds (such as razorbills)" , "Stocky diving birds" .)