Puffin's cousin (3)
I believe the answer is:
auk
'puffin's cousin' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for auk that I've seen before include "Short-winged seabird" , "A seabird from Milwaukee" , "Northern seabird with small narrow wings" , "Great ---, extinct seabird" , "One that flies" .)