Most easily melted sleuth in the grip of wanton cutie (8)

I believe the answer is:

eutectic

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'most easily melted sleuth in' is the definition.
The definition and answer can be both substances as well as being singular nouns.
Maybe you can see a link between them that I don't see?

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Another definition for eutectic that I've seen is " (Of mixture) having a lower melting point than either constituent; cute Ice T (anag.)".)

I've seen this clue in The Sunday Times and The Times.

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