Senior army officer in overall (7)
I believe the answer is:
general
I believe this is a double definition.
'senior army officer' is the first definition.
(I've seen this before)
'overall' is the second definition.
(similar in meaning)
'in' acts as a link.
(Other definitions for general that I've seen before include "Army rank" , "Rank; all-inclusive" , "Applying to all or most of a group" , "blanket" , "Regular - officer" .)