Songster (7)
I believe the answer is:
warbler
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">songster</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for warbler that I've seen before include "18's [BIRD]" , "XWD SETTER" , "songster" , "A small songbird or similar singer" .)