New cadet with our teacher (8)
I believe the answer is:
educator
'teacher' is the definition.
(someone who educates)
'new cadet with our' is the wordplay.
'new' indicates an anagram.
'with' is a charade indicator (letters next to each other).
'cadet' after 'our' is 'ourcadet'.
'ourcadet' is an anagram of 'EDUCATOR'.
(Other definitions for educator that I've seen before include "master, say" , "Trainer, teacher" , "coach" , "One who teaches others" , "mistress, say" .)