Warned of education (9)
I believe the answer is:
cautioned
'warned' is the definition.
(cautioning is a kind of warning)
'of education' is the wordplay.
'of' indicates an anagram (the answer comes from or 'of' the letters).
'education' is an anagram of 'CAUTIONED'.
(Other definitions for cautioned that I've seen before include "Gave warning" , "Education (anag)" , "Warned by way of education" , "Given formal warning" .)