In Bamidbar, 24:10, we read
וַיִּֽחַר־אַ֤ף בָּלָק֙ אֶל־בִּלְעָ֔ם וַיִּסְפֹּ֖ק אֶת־כַּפָּ֑יו וַיֹּ֨אמֶר בָּלָ֜ק אֶל־בִּלְעָ֗ם לָקֹ֤ב אֹֽיְבַי֙ קְרָאתִ֔יךָ וְהִנֵּה֙ בֵּרַ֣כְתָּ בָרֵ֔ךְ זֶ֖ה שָׁלֹ֥שׁ פְּעָמִֽים׃ Enraged at Balaam, Balak struck his hands together. “I called you,” Balak said to Balaam, “to damn my enemies, and instead you have blessed them these three times!
The Judaica Press reads "and he clapped his hands. "
Some of the commentators explain what the word vayispok means, but I can't find any that discusses why the clapping is mentioned. Yes, Balak was angry, but we know that from "vayichar af". Is anything gained by telling us that he also clapped his hands? Other people have been angry in the text but I don't recall that the Torah makes a practice of telling us that they stamped their feet or shrugged their shoulders unless that action was independently important (like Moshe's action of throwing down the Luchot in Sh'mot 32:19).
So why does the clapping matter enough to be mentioned?