Normal departure (7,5)

I believe the answer is:

natural death

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

'normal departure' is the definition.
The definition suggests a singular noun which matches the answer.

'normal departure' is the wordplay.
'normal' becomes 'natural' (similar in meaning).
'departure' becomes 'death' (I can't justify this - if you can you should believe this answer much more).
'natural'+'death'='NATURAL DEATH'

Can you help me to learn more?

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

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.