Diving birds (5)
I believe the answer is:
loons
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">diving birds</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for loons that I've seen before include "Casual bags" , "Birds" , "of similar type to 2 down [NUMBSKULL]?" .)