Large-scale course briefly a focus for seismologist (9)

I believe the answer is:

epicentre

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'a focus for seismologist' is the definition.
I can't judge whether this defines the answer.

'large-scale course briefly' is the wordplay.
'large-scale' becomes 'epic' (I've seen this before).
'course' becomes 'entree' (entree is a kind of course).
'briefly' means to remove the last letter.
'entree' with its last letter removed is 'entre'.
'epic'+'entre'='EPICENTRE'

Can you help me to learn more?

(Other definitions for epicentre that I've seen before include "Shakiest point" , "Point on surface directly over an earthquake" , "hub of quake" , "in the middle" , "Focus of activity" .)

I've seen this clue in The Guardian.

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