Scottish writer’s terror on hearing what lies deep below (10)

I believe the answer is:

barysphere

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'scottish writer's terror' is the definition.
The definition suggests a singular noun which matches the answer.

'on hearing what lies deep below' is the wordplay.
I cannot really understand how this works, but
'on' could be 're' (regarding) and 're' is present in the answer.
This explanation may well be incorrect...

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I've seen this clue in The Times.

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