Clue is ; Occupation of gentlemen-at-arms, historically. (3-7)
Answer is ; Gun running.
I can find no connection between gun-running and gentlemen-at-arms, if anyone could give a better parse than arms being guns. The Times usually has a better parse.
If you go back to the 1400's they were armed with spears and lances.
Couldn't find any reference to guns.Were arms smugglers called Gentlemen-at-arms I wonder.