Hi Don,
A Clarke from Kinnegad, ending up in Newport RI definitely seems like too much of a coincidence alright!
Esther Clarke Keegan, who moved to Rhode Island to be with her son Francis and daughters Mary and Margaret in 1883, died in 1892 and her death cert in Newport listed her parents as Patrick Clarke and Esther. The question is: could her mother be listed incorrectly?
From a preliminary search on rootsireland, Patrick and Margaret Clarke have 3 baptism records in Kinnegad:
1826 Esther (corresponds very well with our Esther as death cert has her birth in 1826)
1830 Richard
1834 Francis (our Esther had a son, Francis, so seems to run in the family).
Add to that Esther's daughter Margaret and we have a matching up of names. It does seem increasingly likely that the death cert had Esther's mother listed incorrectly and it potentially should be Margaret.
The fact that there's a connection to Newport and perhaps that's why Esther's son Francis moved there, does increase the likelihood that your gg-gm Margaret Clarke was our Esther's sister.
However, there were quite a number of Clarkes around Kinnegad and it's common for people in a general area to emigrate to the same place in the US or elsewhere. I think if we can find correlation between our Esther and her children in Rhode Island with your gg-gm Margaret, then we can perhaps tie it down better.
I am in contact with several members of the family, including some who are still in Rhode Island. I will send you a PM.
Talk soon,
Alan.