To Smash, To Break
transitive verb, godan verb
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means smash and the verb vocab version of the kanji is to smash or to break.
くだく
You want to smash my stuff? That's coo' だ (くだ). Whatever you wanna do.
クッキーが粉々になるまで、伸ばし棒で叩いて砕きました。
I smashed the cookies with a rolling pin until they were broken into small pieces.