Most jovial, but with husband descending to become most crude (9)

I believe the answer is:

earthiest

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'most crude' is the definition.
Both the definition and answer are superlative adjectives. Maybe they are linked in a way I don't understand?

I can't explain the rest of the clue.

Can you help me to learn more?

(Another definition for earthiest that I've seen is " The most coarse".)

I've seen this clue in The Times.

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