The mother of all lakes (8)

I believe the answer is:

superior

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'lakes' is the definition.
(I know that Superior is a lakes)

I don't understand how the remainder of the clue works.

(Other definitions for superior that I've seen before include "World's largest freshwater lake" , "One of forty across" , "A better boss?" , "Of greater rank or quality" , "Of high standard" .)

I've seen this clue in The Globe and Mail.

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