Lump of dirt (4)
I believe the answer is:
'lump 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 "Compact mass - stupid person" , "Lump of earth - stupid person" , "Lump of turf" , "Stupid person - compact lump" , "dope?" .)