'During sex ...' an adult person from Porlock interrupted its description (6)

I believe the answer is:

xanadu

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(Other definitions for xanadu that I've seen before include "Kubla Khan's capital as in Coleridge's poem" , "Kublai Khan's capital" , "Place in poem by Coleridge" , "pleasure centre?" , "Imaginary idyll" .)

I've seen this clue in The Independent.

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