Grammer is not CLR(1) because it have Shift-Reduce conflict.
S->c.a $ (Shift production)
A->c. a (Reduce production)
The shift reduce condition in CLR(1) is that Shifting symbol should not be appearing look ahead list of reducing production.
Here 'a' is shift in 1st production and it also appear look ahead list of 2nd production.
And another alternative grammer is ambiguous it have 2 parse tree for the string 'ca' if the grammer is ambigious it can not be CLR(1)