Child given a large sum (5)
I believe the answer is:
total
'sum' is the definition.
(synonyms)
'child given a large' is the wordplay.
'child' becomes 'tot' (term for a young child).
'given' says to put letters next to each other.
'large' becomes 'L' (eg in clothes sizes).
'tot'+'a'+'l'='TOTAL'
(Other definitions for total that I've seen before include "gross" , "Completely destroy" , "French oil and gas company" , "Aggregate amount" , "wreck" .)