Crossword Genius

Child gets out of bed to do sums (3,2)

Ross

I believe the answer is:

tot up

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'to do sums' is the definition.
I can't judge whether this definition defines the answer.

'child gets out of bed' is the wordplay.
'child' becomes 'tot' (term for a young child).
'gets' says to put letters next to each other.
'out of bed' becomes 'up' (synonyms).
'tot'+'up'='TOT UP'

Can you help me to learn more?

(Other definitions for tot up that I've seen before include "Do summer job" , "Add (some numbers)" , "Sum - total" , "Tally" , "Reckon" .)

I've seen this clue in The Globe and Mail.
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