Terra firma (5)
'terra firma' is the definition.
(I know that terra firma can be written as land)
This is all the clue.
(Other definitions for land that I've seen before include "part of surface" , "Come down; territory" , "Lift with ropes and pulleys" , "Terrain" , "people" .)
(Other definitions for earth that I've seen before include "Land" , "Terrestrial sphere" , "Lair; planet" , "underground shelter" , "Familiar example of 1 Across" .)
(Other definitions for ground that I've seen before include "See 14" , "foundation course?" , "The solid surface of the Earth" , "Pulverised; earth" , "Oval, for example" .)