Swamp throwing out gold lump (4)

I believe the answer is:

mass

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'lump' is the definition.
(I have seen 'Lump of material' mean 'mass' so perhaps 'lump' could also mean 'mass')

I can't explain the rest of the clue.

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(Other definitions for mass that I've seen before include "Religious rite" , "Service; horde" , "Christian ritual" , "Accumulation" , "Ceremony for many" .)

I've seen this clue in The Telegraph.

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