Good service that means a lot (4)

I believe the answer is:

mass

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'lot' is the definition.
('mass' can be a synonym of 'lot')

I can't explain the rest of the clue.

(Other definitions for mass that I've seen before include "Church service - crowd" , "Ceremony for many" , "Pound, maybe" , "what 13 15A [STANDARD MODEL] supposes 12 [HIGGS BOSON] gives other 5A [PARTICLES]s" , "Roman Catholic service" .)

I've seen this clue in the Evening Standard.

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