Shrouded in secrecy: an ideal murder weapon? (7)

I believe the answer is:

cyanide

I'm a little stuck... Click here to teach me more about this clue!

'murder weapon?' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.

'shrouded in secrecy an ideal' is the wordplay.
'shrouded in' says the answer is hidden in the clue.
'CYANIDE' is hidden within 'secrecy an ideal'.

Can you help me to learn more?

(Other definitions for cyanide that I've seen before include "Extremely poisonous salt" , "Toxic salt" , "Nice day (anag) - poison" , "Highly toxic substance" , "Poisonous compound" .)

I've seen this clue in The Times.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.