The samurai told me he would cut off my tongue if I couldn’t say the tongue twister properly.
Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means slice and the verb vocab version means to cut down or to slice off or to lop off. This word mainly refers to cutting people with a sword, if you haven't figured it out yet.
The reading is the same as 切る, which means "to cut." Similar meaning, same reading.