。
She quickly shut the kitten inside the basket.
Literal
She [topic-は] quickly kitten [object-を] basket [genitive-の] inside [in-に] shut-in.
閉じ込める is a compound verb: 閉じる ('close / shut') + 込める ('put in / put into'). Together: 'shut into / confine inside'. The pattern compound-verb-with-~込める shares territory with ~込む but is transitive — the actor confines someone or something. 籠の中に ('inside the basket') uses the relative-position frame Xの中 ('inside X'); the に marks the destination of the shutting-in motion. 子猫 ('kitten') is a transparent compound: 子 ('child') + 猫 ('cat').