Crossword Genius

Not a peaceful departure (7,5)

Ross

I believe the answer is:

violent death

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

'not a' is the definition.
I can't tell whether this definition defines the answer.

'peaceful departure' is the wordplay.
'peaceful' becomes 'violent' (I can't justify this - if you can you should give a lot more credence to this answer).
'departure' becomes 'death' (I've seen this in another clue).
'violent'+'death'='VIOLENT DEATH'

Can you help me to learn more?

I've seen this clue in The Globe and Mail.
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