Goofus (3)
I believe the answer is:
oaf
'goofus' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for oaf that I've seen before include "Oik" , "Stupid lout" , "Stupid or clumsy man" , "Lout; dolt" , "Boor or lout" .)