Concerning a seaman getting dismissed (5)
I believe the answer is:
about
'concerning' is the definition.
(about can mean concerning or relating to)
'a seaman getting dismissed' is the wordplay.
'a seaman' becomes 'ab' (short for able seaman).
'getting' is a charade indicator (letters next to each other).
'dismissed' becomes 'out' (dismissed in cricket).
'ab'+'out'='ABOUT'
(Other definitions for about that I've seen before include "Concerning or around" , "In conection with, all around" , "Concerning or in neighbourhood" , "On the subject of, approximately" , "not far away" .)