Before service, sailor curses? (5)
I believe the answer is:
abuse
'curses?' is the definition.
(cursing or swearing is verbal abuse)
'before service sailor' is the wordplay.
'before' means one lot of letters go next to another.
'service' becomes 'use' (I've seen this in other clues).
'sailor' becomes 'ab' (abbreviation for able seaman).
'use' put after 'ab' is 'ABUSE'.
(Other definitions for abuse that I've seen before include "Given poor treatment" , "Vilify" , "Castigate" , "Treat badly; insult" , "corrupt practice" .)