You could be right, but I also found Clamma in use as a female name. I didn't find any meaning however. Also I found Clamma and Mc Clamma as a surname.
Clammas is an English dialect word:
CLAMMAS, V. To climb (n.Cj'.).
http://www.archive.org/stream/englishdialectdi01wrig/englishdialectdi01wrig_djvu.txt