From Wiktionary, the free dictionary
From clap + along; compare singalong.
clapalong (plural clapalongs)
- (rare) A musical performance which the audience is encouraged to accompany by clapping the hands.
2007 July 2, Jon Pareles, “Everyone Join In: Sing, Clap and Hug”, in New York Times[1]:He cued clapalongs, singalongs and synchronized arm movements.
