、。
After dinner, Dad quietly called George aside.
Literal
Dinner-after, father [topic-は] George [object-を] stealthily call-out-[past-した].
こっそり(と) is a state mimetic (擬態語) for doing something stealthily, quietly, in secret — 'on the sly.' Common in storytelling for sneaking or surreptitious action. 呼び出す ('to call out, summon') is a compound verb: 呼ぶ ('call') + 出す ('bring out'). The combination evokes an image of separating the target from a group — pulling George aside for a private word.