Killed (5)
'killed' is the definition.
(slaying is a kind of killing)
This is the entire clue.
(Other definitions for slain that I've seen before include "Violently killed" , "Slaughtered" , "Killed, murdered" , "Put to the sword" .)
'killed' is the definition.
(historical past tense of slay)
This is all the clue.
(Other definitions for slew that I've seen before include "Cut down" , "Killed (arch.)" , "skid" , "lot of Americans" , "Butchered" .)