The King gets Queen to kick out international junior swimmers (6)

I believe the answer is:

elvers

I'm a little stuck... Click here to teach me more about this clue!

'swimmers' is the definition.
(elver is a kind of aquatic vertebrate)

'the king gets queen to kick out international junior' is the wordplay.
I cannot quite understand how this works, but
'king' could be 'er' (abbreviation for Edward Rex, various English kings) and 'er' is found within the answer.
This explanation may well be incorrect...

Can you help me to learn more?

(Another definition for elvers that I've seen is " Young eels".)

I've seen this clue in The Independent.

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