Rank greatness in officers (9)
I believe the answer is:
sergeants
'officers' is the definition.
(sergeant is a kind of officer)
'rank greatness' is the wordplay.
'rank' indicates an anagram (a rank or rotten spelling of the letters).
'greatness' with letters rearranged gives 'SERGEANTS'.
'in' acts as a link.
(Other definitions for sergeants that I've seen before include "Greatness observed in NCOs" , "Odd greatness of these army and police ranks" , "Greatness among NCOs" .)