Fatty excess in US — hear robes must be altered (9)

I believe the answer is:

seborrhea

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This clue might be a double definition.

'fatty excess in us' is the first definition.
The definition suggests a singular noun which matches the answer.

'hear robes must be altered' is the second definition.
I can't tell whether this definition defines the answer.

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

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