What XL represents generally speaking (2,3,5)

I believe the answer is:

by and large

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'generally speaking' is the definition.
(thesaurus)

I cannot understand how the remainder of the clue works.

(Other definitions for by and large that I've seen before include "On the whole" , "In the main" , "Speaking generally" , "As a rule" , "In general" .)

I've seen this clue in The Independent.

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