Global seminar is among the very best (5-5)

I believe the answer is:

world-class

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'among the very best' is the definition.
(I've seen this in another clue)

'global seminar' is the wordplay.
'global' becomes 'world' (I can't explain this - if you can you should give a lot more credence to this answer).
'seminar' becomes 'class' (I've seen this before).
'world'+'class'='WORLD-CLASS'

'is' is the link.

Can you help me to learn more?

I've seen this clue in The Times.

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