Process by which barnacle is made bare? (12)

I believe the answer is:

desalination

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'process' is the definition.
(desalination is a kind of process)

'by which barnacle is made bare?' is the wordplay.
I cannot really see how this works, but
'by' could be 'at' and 'at' is found in the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?

(Another definition for desalination that I've seen is " Activity of water company".)

I've seen this clue in The Times.

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