Singing Circles Ireland
https://facebook.com/groups/852693051408846

2016 list from Comhaltas Rochester
http://irishrochester.weebly.com/singers-sessions.html

You might get some leads on Sean's Singing Session Videos page
https://facebook.com/seanmcboc/

A search for circle on The Folk Club Map gets about twenty Singing Circle results in Ireland.
Copy the link and paste it in to a browser; use landscape format.
www.google.com/maps/d/u/0/viewer?mid=1Tf5UnYW2tZqJO6qcaMDdT3v-4D8JutUK
There are probably other singing sessions there which don't use the word circle ;)

The Etiquette At Singing Sessions Of Traditional Irish Songs
www.enjoy-irish-culture.com/Traditional-Irish-songs.html