Relating to birds (5)
I believe the answer is:
avian
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">relating to birds</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for avian that I've seen before include "Like rails, for example" , "Resembling a bird" , "Relating to birds" , "Regarding birds" , "Pertaining to or characteristic of birds" .)