Indiscreet novel, extraordinarily colourful (10)

I believe the answer is:

iridescent

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'extraordinarily colourful' is the definition.
'iridescent' can be an answer for 'colourful' ('iridescent' can be similar in meaning to 'colourful'). I am unsure of the 'extraordinarily' bit.

'indiscreet novel' is the wordplay.
'novel' indicates an anagram.
'indiscreet' with letters rearranged gives 'IRIDESCENT'.

Can you help me to learn more?

(Other definitions for iridescent that I've seen before include "flashing colours" , "Shimmering with rainbow colours (anag of 1 across, 9 and 23)" , "Showing luminous colours" , "Eye-catching" , "Like a rainbow" .)

I've seen this clue in The Telegraph.

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