Wrong head chopped off monster (5)
I believe the answer is:
error
This clue might be a double definition.
'wrong' is the first definition.
(I've seen this before)
'head chopped off monster' is the second definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
Can you help me to learn more?
(Other definitions for error that I've seen before include "Slip, mistake" , "heresy" , "Bug" , "Way of operating" , "Boo-boo" .)