Possible Clues:

• Business abbreviation for headless gangster in the barracks
• Rank below sergeant
• Officer said to support my promotion, initially
• Soldier finding two rivers entering part of sea?
• Sergeant's inferior
• Private instructor, at times
• Rank expert back in the pink
• Soldier material
• Klinger of 'M*A*S*H,' e.g
• Noncommissioned officer in the Army