Component (a building block) — not the same thing as a radical or a sound component. · 5strokes
究穷帘挖空穿突窃
Kangxi radical no.116 · 5strokes — The 214 Kangxi radicals
Filed under it in a dictionary. That is a lookup convention — it does not mean it is the only part the character is built from.
穴究穷空穿突窃窄