Full shadow (5)
I believe the answer is:
umbra
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">full shadow</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 umbra that I've seen before include "Rumba (anag.)" , "Shadow's inner region" , "Dark shadow cast by earth in eclipse" , "shady region" , "Shade, or ghost" .)