Mooring to clean off accumulated mass (14)

I believe the answer is:

conglomeration

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

'accumulated mass' is the definition.
'conglomeration' can be an answer for 'mass' (thesaurus). I'm not certain of the 'accumulated' bit.

'mooring to clean off' is the wordplay.
'off' is an anagram indicator.
'mooring'+'to'+'clean'='mooringtoclean'
'mooringtoclean' is an anagram of 'CONGLOMERATION'.

Can you help me to learn more?

(Other definitions for conglomeration that I've seen before include "pile" , "Large group of merged companies" , "Collection or jumble of things" , "Gathering" .)

I've seen this clue in the Sydney Morning Herald.

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