Ray of light (4)
(Other definitions for sunbeam that I've seen before include "Ray of natural light" , "sheds a bit of light" , "Bright shaft of daylight" , "Ray of solar light" , "Bright ray -- bus name (anag)" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ray of light</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know this)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for beam that I've seen before include "Radiant smile; timber support" , "Shine" , "Supporting structure" , "XWD SETTER" , "Ray of light or a large smile" .)