Colour of line round centre of Earth (5)

I believe the answer is:

ochre

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

'colour' is the definition.
(ochre is a kind of colour)

'line round centre of earth' is the wordplay.
'line' becomes 'och' (I can't explain this - if you can you should give a lot more credence to this answer).
'round' becomes 'orb'.
'centre of' says to take the centre.
'earth' becomes 'E'.
The middle of 'orb' is 'r'.
'och'+'r'+'e'='OCHRE'

'of' is the link.

Can you help me to learn more?

(Other definitions for ochre that I've seen before include "Pigment made from clay and iron oxide" , "What gives a yellow colour" , "Orange-yellow colour" , "natural colouring" , "Yellow-red earthy pigment" .)

I've seen this clue in The Telegraph.

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.