A Carib tongue (6)
I believe the answer is:
arabic
'tongue' is the definition.
(I know that Arabic is a type of Semitic)
'a carib' is the wordplay.
'a carib' anagrams to 'ARABIC'.
However, I'm not sure how this is indicated.
Can you help me to learn more?
(Other definitions for arabic that I've seen before include "Official language of Egypt" , "connected with gum" , "Language of the Koran" , "Semitic language" , "Language (of numbers)" .)