Signal fire or light (6)
I believe the answer is:
beacon
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">signal fire</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">light</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for beacon that I've seen before include "Warning fire or signal" , "Shining light (on top of a hill?)" , "Warning light on hill or cliff" , "Fire on a hill, lit as a signal" , "A warning light as on headland" .)