A crab managed, having one tongue (6)
I believe the answer is:
arabic
'tongue' is the definition.
(Arabic is an example)
'a crab managed having one' is the wordplay.
'managed' indicates anagramming the letters.
'having' is an insertion indicator.
'one' becomes 'I' (Roman numeral).
'crab' is an anagram of 'rabc'.
'rabc' enclosing 'i' is 'rabic'.
'a'+'rabic'='ARABIC'
(Other definitions for arabic that I've seen before include "CIA bar on this Middle East language" , "Major language of Middle East" , "There's a CIA bar on this language, oddly" , "Middle Eastern language" , "connected with gum" .)