Colourful instrument for a novice (9)

I believe the answer is:

greenhorn

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'for a novice' is the definition.
(greenhorn is a kind of novice)

'colourful instrument' is the wordplay.
'colourful' becomes 'green' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'instrument' becomes 'horn' (horn is a kind of instrument).
'green'+'horn'='GREENHORN'

Can you help me to learn more?

(Other definitions for greenhorn that I've seen before include "Novice" , "An inexperienced person of emerald hue?" , "Tenderfoot" , "Naive person (US)" , "Rookie (American)" .)

I've seen this clue in The Globe and Mail.

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