Spirits: senior officer takes two (5)
I believe the answer is:
genii
'spirits' is the definition.
(plural of genie or genius)
'senior officer takes two' is the wordplay.
'senior officer' becomes 'gen' (short for general, a senior army officer).
'takes' means one lot of letters go next to another.
'two' becomes 'ii' (roman numeral).
'gen'+'ii'='GENII'
(Other definitions for genii that I've seen before include "Personal spirits" , "masterminds" , "Spirits such as Aladdin's" , "Perhaps boy wonders" , "bottled spirits" .)