Dunce is dancing it off, twerking at the head (5)
I believe the answer is:
idiot
'dunce' is the definition.
(I've seen this in another clue)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for idiot that I've seen before include "Silly ass" , "Clot" , "Fool, silly person" , "'The -----'. novel by Dostoyevsky (1868)" , "The - (Dostoievsky)" .)