Better people in education (5)
I believe the answer is:
Here is my best explanation:
'better' is the definition.
(emending is a kind of bettering)
'people in education' is the subsidiary indication.
'people' becomes 'men' (man is a kind of person).
'in' is an insertion indicator.
'education' becomes 'ed' (abbreviation - e.g. sex ed).
'men' placed within 'ed' is 'emend'.
(Other definitions for emend that I've seen before include "Correct and improve the text", "make corrections", "Alter something written to correct errors", "Make correction in written material", "Rectify", "Change", "Edit; make alterations to a draft", "Correct, revise (text)", "Improve (texts)" and "Make alterations".)