Dummkopf (5)
I believe the answer is:
moron
'dummkopf' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for moron that I've seen before include "Somewhat feeble-minded person" , "Halfwit" , "Clot" , "Blockhead" , "Simpleton" .)