For the military man, it's confidential (7)
I believe the answer is:
private
I believe this clue is a double definition.
'for the military man' is the first definition.
(private is a kind of military man)
'confidential' is the second definition.
(similar in meaning)
'it's' is the link.
(Other definitions for private that I've seen before include "Clandestine" , "retiring" , "Not to be shared or revealed" , "Arm y rank" , "Ordinary soldier" .)