Small drink for a small child (3)
I believe the answer is:
tot
This clue is a double definition.
'small drink' is the first definition.
(I've seen this in another clue)
'small child' is the second definition.
(tot can mean a baby or toddler)
'for a' acts as a link.
(Other definitions for tot that I've seen before include "Get the sum for the toddler" , "Tiny child" , "finger, possibly" , "Get the sum for the child" , "Child; measure of spirits" .)