One hoping you buy second drinks for each child (11)
I believe the answer is:
salesperson
'one hoping you buy' is the definition.
'second drinks for each child' is the wordplay.
'second' becomes 's' (common abbreviation).
'drinks' becomes 'ales' (ale is a kind of drink).
'for each' becomes 'per' (I've seen this before).
'child' becomes 'son' (son is a kind of child).
's'+'ales'+'per'+'son'='SALESPERSON'
(Other definitions for salesperson that I've seen before include "Commercial traveller possibly" , "Shop assistant" , "Shop attendant" , "One must try to improve business" , "Retail worker" .)