Inner planet (5)
(Other definitions for mars that I've seen before include "part of suite" , "Spoils - heavenly body" , "Spoils - planet" , "March to the French" , "War god - chocolate bar - spoils" .)
(Other definitions for earth that I've seen before include "Badger or fox burrow" , "dirt" , "Heart of clay" , "Solid ground" , "Terrestrial sphere" .)
(Other definitions for venus that I've seen before include "Brightest planet" , "Heavenly body" , "Solar system planet" , "not really a star" , "our Neighbour" .)