Not a little bounder, but a potential officer (5)

I believe the answer is:
cadet
'potential officer' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for cadet that I've seen before include "Armed services trainee" , "Potential officer" , "Trainee soldier" , "Police force trainee" , "A trainee army officer" .)
