They kill members (4)
I believe the answer is:
arms
I believe this clue is a double definition.
'they kill' is the first definition.
(arms can mean weapons)
'members' is the second definition.
(arm is a kind of member)
(Other definitions for arms that I've seen before include "Blazonry; weaponry" , "George Bernard Shaw play '. . . . and the Man'" , ". . . . and The Man (G.B. Shaw)" , "Supplies weapons" , ". . . . and the Man (G B Shaw) (4)" .)