Pulled a dagger, very nastily, on a dunderhead! (7)
I believe the answer is:
dragged
'pulled a' is the definition.
I can't judge whether this definition defines the answer.
'dagger very nastily on a dunderhead' is the wordplay.
I cannot really understand how this works, but
an anagram of 'dagger' is 'dragge' which is within the answer.
'dunderhead' could be 'd' (head letter of 'dunder') and 'd' is present in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for dragged that I've seen before include "Pulled along roughly" , "Drew slowly or heavily" , "Hauled" , "Trailed" .)