Complex sentence: One of the first songs she was asked to write was a half-spoken, half-sung song, Gabbin "Blues" sung by Big Maybelle with the talking part provided by Rose Marie McCoy.
Split into simpler sentences: One of the first songs she was asked to write was a half-spoken half-sung song. Her Gabbin "Blues" was sung by Big Maybelle and the talking part was provided by Rose Marie McCoy.