Reptile in zoo died, replaced by aardvark ultimately (4,5)

I believe the answer is:

whip snake

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

'reptile' is the definition.
(whip snake is a kind of reptile)

'in zoo died replaced by aardvark ultimately' is the wordplay.
I cannot quite see how this works, but
'in' could be 'hip' (both can mean fashionable) and 'hip' is located in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in The Independent.

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