Crossword Genius

Indigo for a chess computer (4,4)

Ross

I believe the answer is:

deep blue

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

This clue might be a double definition.

'indigo' is the first definition.
(indigo is a dark shade of blue)

'chess computer' is the second definition.
'deep blue' can be an answer for 'computer' (I've seen this before). I am unsure of the 'chess' bit.

'for a' is the link.

Can you help me to learn more?

(Another definition for deep blue that I've seen is " Computer".)

I've seen this clue in The Guardian.
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