This was Tennyson's main memoir rewritten (2,8)

I believe the answer is:

in memoriam

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'this was tennyson's' is the definition.
The definition suggests a singular noun which matches the answer.

'main memoir rewritten' is the wordplay.
'rewritten' indicates an anagram.
'main'+'memoir'='mainmemoir'
'mainmemoir' anagrammed gives 'IN MEMORIAM'.

Can you help me to learn more?

(Another definition for in memoriam that I've seen is " Tennyson poem, for A. H. H.".)

I've seen this clue in The Independent.

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