Handle idiot (4)
I believe the answer is:
knob
I believe this is a double definition.
'handle' is the first definition.
(knob is a kind of handle)
'idiot' is the second definition.
(both are insults)
(Other definitions for knob that I've seen before include "Handle or dial" , "Protuberance" , "Prominent rounded hill" , "Rounded projection" , "Round door handle or lump of butter" .)