Non-commissioned officer wanting ten gears, possibly (8)
I believe the answer is:
sergeant
'non-commissioned officer' is the definition.
(I know that sergeant is a type of non-commissioned officer)
'wanting ten gears possibly' is the wordplay.
'wanting' means one lot of letters go next to another.
'possibly' indicates an anagram.
'ten'+'gears' is 'tengears'.
'tengears' is an anagram of 'SERGEANT'.
(Other definitions for sergeant that I've seen before include "Rank above corporal" , "CARRY ON FILM" , "NCO or police officer ..." , "Man in charge" , "Reagents for army NCO" .)