Matlo Herb afloat is salt of wisdom! (9)

I believe the answer is:

alembroth

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

'salt of wisdom' is the definition.
'alembroth' can be an answer for 'salt' (I've seen this before). I'm not sure about the 'of wisdom' bit.

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for alembroth that I've seen before include "Double salt" , "salt of wisdom!" .)

I've seen this clue in The Times and The Sunday Times.

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