:a fact or statement that makes something certain or final起决定性作用的事实（或陈述）
This delicious soup is bound to impress guests. And here's the clincher: it's very easy to make. [=the fact that the soup is easy to make makes it especially appealing]这道美味的汤肯定会让客人们印象深刻。关键在于它做起来还很简单。