Luminous ring (4)
I believe the answer is:
halo
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">luminous ring</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 halo that I've seen before include "Circle over a saint" , "Ring of light (signifying holiness)" , "Imaginary circle over saint's head" , "Ring (around sun or moon)" , "Aura representing saintliness" .)