Fiqh-us-Sunnah Volume 2, Supererogatory Prayer, Fiqh 2.086.

It is allowed for men to say subhanallah and for women to clap if there is some need to do so (such as alerting the imam to a mistake or informing someone that he or she may enter the room or to warn a blind person, and so on). Sahl ibn Sa’d asSa’di relates that the Prophet said: “If someone is faced with something during the salah, he should say ‘subhanallah.’ Clapping is for the women and saying subhanallah is for the men.” This is related by Ahmad, Abu Dawud, and an-Nasa’i.