Fear wrongdoing under head teacher (6)
I believe the answer is:
terror
'fear' is the definition.
(terror is a kind of fear)
'wrongdoing under head teacher' is the wordplay.
I cannot quite see how this works, but
'wrongdoing' could be 'error' (synonyms) and 'error' is located in the answer.
A single letter 't' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for terror that I've seen before include "Little brat" , "Extreme or intense fear" , "Young rascal -- horror" , "Utter dread" , "Young miscreant" .)