New cadet or old soldier (7)
I believe the answer is:
redcoat
'old soldier' is the definition.
(I've seen this before)
'new cadet or' is the wordplay.
'new' is an anagram indicator.
'cadet'+'or'='cadetor'
'cadetor' anagrammed gives 'REDCOAT'.
(Other definitions for redcoat that I've seen before include "British soldier (hist.)" , "British soldier (historical)" , "British soldier or Butlin's worker" , "One employed to entertain" , "Old British soldier - Butlin's entertainment organiser" .)