Soldier and sailor returning after leave (6,3)
I believe the answer is:
desert rat
'soldier' is the definition.
(nickname for a soldier from 7th Armoured Division)
'sailor returning after leave' is the wordplay.
'sailor' becomes 'tar' (slang term for a sailor).
'returning' says the letters should be written in reverse.
'after' means one lot of letters go next to another.
'leave' becomes 'desert' (deserting is a kind of leaving).
'tar' back-to-front is 'rat'.
'rat' after 'desert' is 'DESERT RAT'.
'and' acts as a link.
(Other definitions for desert rat that I've seen before include "Soldier in the North African campaign (nineteen forty one to nineteen forty two)" , "Tommy" , "One of Rommel's nemesis" , "Old soldier" , "See soldier" .)