Here is the full 1851 census entry
1851 Ramsey
, 01-26, 094, Water St
CLARKE, Ewan,, Head, Married, 59, Corn Dealer, Lezayre
CLARKE, Ann, , Wife, Married, 55, , Andreas
CAIN, Christian, Daughter, Married, 24, Master Mariners Wife, Ramsey
CLARKE, Ann, Daughter, , 22, Milliner, Ramsey
CLARKE, Margaret E, , Daughter, , 20, , Ramsey
CLARKE, William, son, , 16, Bakers Appt, Ramsey
CASEMENT, John, , Lodger, , 12, Scholar, England
FARGHER, Horatio, , Nephew, , 3, Scholar, Maughold

Jame's sister Christian had been md 25 Sep 1850 Lezayre to Capt William Caine.
Lezayre MI
Old Yard #597
Sacred to the memory of Eliza Clark the daughter of Ewan Clark
and Ann Clark alias Christian his wife who departed this life August the 4th 1831 aged 8 years
In memory of Capt.William Caine who was lost on his passage to Africa Oct 7th 1850
Also Christian Caine alias Clarke wife of the above who died July 10th 1858 aged 32 years

I don't know what Cain(e) line William was from.

You'll note that Clark(e) like Cain(e) has the floating e. in various records.

Donna