Hilltop fire (6)
I believe the answer is:
beacon
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hilltop fire</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 beacon that I've seen before include "Warning, guiding, fire" , "Warning light on tower or hill" , "Warning fire or signal" , "A warning light as on headland" , "Signal fire - lighthouse" .)