High-minded headmaster dismissing a limited version of education? (10)

I believe the answer is:

principled

'high-minded' is the definition.
(thesaurus)

'headmaster dismissing a limited version of education?' is the wordplay.
I cannot quite see how this works, but
'education?' could be 'ed' (abbreviation - e.g. sex ed) and 'ed' is found within the answer.
This explanation may well be incorrect...

(Another definition for principled that I've seen is " With justification".)

I've seen this clue in The Times.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.