Young bird, not yet fledged (8)
I believe the answer is:
nestling
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">young bird not yet fledged</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for nestling that I've seen before include "Young bird - snuggling" , "not yet put out" , "Young bird not yet fledged" , "Unfledged bird" , "getting under duvet?" .)