Clump of dirt (4)
I believe the answer is:
clod
'clump of dirt' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for clod that I've seen before include "Lump of earth - nitwit" , "Lump of mud" , "dunce" , "Stupid person - compact lump" , "Lump of earth/clay" .)