Clumsy fool (3)
I believe the answer is:
oaf
'clumsy fool' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for oaf that I've seen before include "A clumsy or stupid person" , "Lout, dullard" , "Stupid lout" , "Stupid or loutish person" , "Lout; dolt" .)