Active summit in Vietnam (4)

I believe the answer is:

etna

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'active summit' is the definition.
The answer and definition can be both locations as well as being singular nouns.
Perhaps you can see a link between them that I don't see?

'in vietnam' is the wordplay.
'in' says the answer is hidden in the clue.
'ETNA' can be found hidden inside 'vietnam'.

Can you help me to learn more?

(Other definitions for etna that I've seen before include "Mount . . . . is a volcano in Sicily" , "Active European volcano" , "burning mountain" , "Highest active volcano in Europe" , "Volcanic mount in Sicily" .)

I've seen this clue in The Independent.

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