Cousin of a bittern (5)
I believe the answer is:
egret
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">cousin of a bittern</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 egret that I've seen before include "Wading bird like a heron" , "Stork-like bird" , "Kind of white heron - greet it" , "Wader with white plumage" , "White, plumed waterbird" .)