During the summing up, as well (2,8)

I believe the answer is:

in addition

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'as well' is the definition.
(thesaurus)

'during the summing up' is the wordplay.
'during' becomes 'in' (e.g. during February means in February).
'the summing up' becomes 'addition' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'in'+'addition'='IN ADDITION'

Can you help me to learn more?

(Another definition for in addition that I've seen is " Also".)

I've seen this clue in the Evening Standard.

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