Killing leaves bar on edge (7)
I believe the answer is:
hemlock
'killing' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'bar on edge' is the wordplay.
'bar' becomes 'lock' (I've seen this in other clues).
'on' says to put letters next to each other.
'edge' becomes 'hem' (a hem is an edge on a piece of cloth).
'lock' after 'hem' is 'HEMLOCK'.
'leaves' acts as a link.
Can you help me to learn more?
(Other definitions for hemlock that I've seen before include "Poisonous weed" , "preparation to kill" , "Poisonous drug" , "Socrates's poison" , "Poisonous plant" .)