What is the ruling on one who directs people to a female singer to perform at a wedding that is free of musical instruments, but not free of rhythm and common song lyrics?

Singing at a wedding is permissible if the rhythm is provided by tambourines (duffs) or human voices, and the lyrics are free from forbidden elements such as obscenity or incitement to evil. However, if the singing includes something forbidden, such as indecent words, or if strange men are present, or if musical instruments are used, then it is not permissible. And whoever knows its condition is not allowed to direct others to it.