Army man's retiring (7)
I believe the answer is:
private
This clue is a double definition.
'army man's' is the first definition.
(type of soldier)
'retiring' is the second definition.
(I've seen this before)
(Other definitions for private that I've seen before include "Confidential sort of soldier" , "Arm y rank" , "Rank, concealed" , "Soldier; personal" , "Clandestine" .)