In the Federal Census of 1790, Clarke Cornell is at Newport; the household consists of 1 male under 16, 1 male over 16, and 1 female, all white. We could assume this is Clarke, Clemence, and Benjamin C. He is listed next to Gideon Cornell (one of 3 in Newport).
According to Clemence's Family Bible, Clarke died at age 37.
There is a birth record at Portsmouth for Clarke Cornell, son of Clarke & Priscilla Cornell, but the dob is 2 Feb 1750/51. Is this the same individual? If so, his dob in Clemence's Bible record is incorrect. I suspect it's a different person.