Question a route winding midline? (7)

I believe the answer is:

equator

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

'midline?' is the definition.
I can't tell whether this defines the answer.

'question a route winding' is the wordplay.
'question' becomes 'q'.
'winding' is an anagram indicator.
'q'+'a'+'route'='qaroute'
'qaroute' anagrammed gives 'EQUATOR'.

Can you help me to learn more?

(Other definitions for equator that I've seen before include "Earth's north-south dividing line" , "Imaginary line around the centre of the earth" , "It's at zero degrees latitude" , "Notional line drawn around the earth" , "Line of zero latitude" .)

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

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