Extremely variable sunrise on inferior planet (5)

I believe the answer is:

venus

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'inferior planet' is the definition.
(Venus is an example)

'extremely variable sunrise' is the wordplay.
'extremely' suggests removing the centre.
'sunrise' becomes 'nus' (I can't explain this - if you can you should believe this answer much more).
'variable' with its middle taken out is 've'.
've'+'nus'='VENUS'

'on' is the link.

Can you help me to learn more?

(Other definitions for venus that I've seen before include "Planet; goddess" , "Evening star" , "Second nearest planet to the sun" , "our Neighbour" , "Next planet in" .)

I've seen this clue in the Sydney Morning Herald.

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