Concerning a sailor away from home (5)
I believe the answer is:
about
'concerning' is the definition.
(about can mean concerning or relating to)
'a sailor away from home' is the wordplay.
'a sailor' becomes 'ab' (abbreviation for able seaman).
'away from home' becomes 'out' (synonyms).
'ab'+'out'='ABOUT'
(Other definitions for about that I've seen before include "not far away" , "Approximately, or in vicinity" , "Concerning or around" , "In the area of or in relation to" , "Concerning or in neighbourhood" .)