Source of daylight (3)
I believe the answer is:
sun
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">source of daylight</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 sun that I've seen before include "Star; newspaper" , "Shiny" , "Star that provides light and heat for a solar system" , "Rag" , "British publication" .)