White privilege ultimately seen in small child having everything (3,4)
I believe the answer is:
cue ball
'white' is the definition.
(the cue ball in snooker is also called the white)
'privilege ultimately seen in small child having everything' is the wordplay.
'ultimately' says to take the final letters.
'seen in' is an insertion indicator.
'small child' becomes 'cub' (cub can mean a baby or child).
'having' means one lot of letters go next to another.
'everything' becomes 'all' (all things).
The final letter of 'privilege' is 'e'.
'e' placed inside 'cub' is 'cueb'.
'cueb'+'all'='CUE-BALL'
(Other definitions for cue ball that I've seen before include "Object struck by a snooker player" , "Jimmy White's white?" , "Feature of pub entertainment" , "The white in snooker" .)