Young genius's wife insufficiently loving (10)

I believe the answer is:

wunderkind

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'young genius's' is the definition.
(I've seen this in another clue)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for wunderkind that I've seen before include "Perhaps Mozart" , "Child prodigy" , "One having early success" , "Clever young person" , "Extraordinary issue" .)

I've seen this clue in The Independent.

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