"clapped in unison" is a perfectly acceptable phrase to use in written English.
You would typically use it to describe a situation where a group of people clapped their hands together in order to express agreement or appreciation. For example, "The crowd clapped in unison when the winning team was announced."
Outside, on East Eleventh Street, a group of guys clapped, in unison, and chanted, "We saw Bugg!
The song conflates a romantic affair with a day on a film set, and when Mr. Gibbard described the director's slate snapping shut, he and Ms. Lewis clapped in unison on the backbeat.
The Nets players and coaches clapped in unison to begin this morning's practice, still buzzing from their rout of the Milwaukee Bucks on Saturday in Game 1 of the Eastern Conference playoffs.
As the race began, a local gospel group, Voices of Life, swayed and clapped in unison on a temporary stage next to the starting line, singing "the Jesus in me loves the Jesus in you" and directing spectators to "praise him and let everyone know that Washington Heights is still the bomb".
Soon the entire crowd swayed and clapped in unison, in a display of Ghanaian spirit and warmth.
Shortly before midnight, though, those in the Senate gallery erupted in cheers and soon began clapping in unison.
Mercury got 75,000 people clapping in unison to "Radio Ga Ga" and "Crazy Little Thing Called Love".
Students show their appreciation at every game by chanting Graham's name in the second half and by clapping in unison.
The remaining fans whistled and cheered, clapping in unison as she reached the final quarter of the track.
After every goal the crowd claps in unison and – if the Supreme Leader is present – the whole of the scoring team rushes forward to stand before him and salute.
As the intermission dragged on for more than 40 minutes, some audience members started clapping in unison to prod him to reappear.
