Gold colour for good sign (7)

I believe the answer is:

auspice

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'sign' is the definition.
(I know that auspice is a type of sign)

'gold colour for good' is the wordplay.
'gold' becomes 'Au' (Au is the chemical symbol for gold).
'colour for good' becomes 'spice' (I can't explain this - if you can you should give a lot more credence to this answer).
'au'+'spice'='AUSPICE'

Can you help me to learn more?

(Other definitions for auspice that I've seen before include "Omen; epic USA (anag.)" , "Omen (archaic)" , "future promise" , "sponsorship" , "Omen - I use cap (anag)" .)

I've seen this clue in The Telegraph.

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