clench
verb (used with object)
to close (the hands, teeth, etc.) tightly.
Used to describe an ongoing action or state that is currently taking place in the immediate present.
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
At last I run into a house with some French soldiers who are clenching their hands with rage at that Taube's behaviour.
From A Woman's Experience in the Great War by Louise Mack