Very bright (5)
I believe the answer is:
vivid
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">very bright</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 vivid that I've seen before include "Intensely striking in colour" , "Strong and bright, colour perhaps" , "Very bright and colourful" , "Intense" , "Intensely deep/bright" .)