World (5)
I believe the answer is:
earth
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">world</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that Earth is a terrestrial planet)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for earth that I've seen before include "our home" , "our present abode" , "Lair; planet" , "Land" , "Terrestrial sphere" .)