Red Planet (4)
I believe the answer is:
mars
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">red planet</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for mars that I've seen before include "Spoils - heavenly body" , "blights" , "Roman war god; planet" , "Spoils - planet" , "Injures - god of war" .)