TOW (& Answer)...

This week’s question was what is Qawwali? To quote directly from our source:

"Qawwali is the Sufi music of India and Pakistan.  Essentially it is religious poetry set to music, sharing certain traits with the light classical music of the subcontinent.  But its sound, with its typically sweeping melodies and rhythmic hand-clapping, is quite distinctive and instantly recognizable." 

Find more about Qawwali, and other music forms, in World Music: The Rough Guide.  The book was published by Rough Guides in 1994 and the question (and answer) were found on p. 222.