Murderers doing away with fifty foreigners? (9)
I believe the answer is:
strangers
'foreigners?' is the definition.
(foreigner is a kind of stranger)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for strangers that I've seen before include "Foreigners" , "Aliens" , "People one doesn't know" , "Outsiders" , "Those we have not met" .)