Country locked between plateaus triangularly (7)

I believe the answer is:

austria

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'country' is the definition.
(Austria is an example)

'between plateaus triangularly' is the wordplay.
'between' indicates a hidden word.
'AUSTRIA' is hidden within 'plateaus triangularly'.

'locked' is the link.
This may not be correct. It may be part of another bit of the clue.

Can you help me to learn more?

(Other definitions for austria that I've seen before include "USA art I send to European state" , "Its ruling house was the Hapsburgs" , "Mountainous European state" , "Central European country" , "Capital city is Vienna" .)

I've seen this clue in The Hindu.

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