The French can get this old language (5)
I believe the answer is:
latin
'this old language' is the definition.
(Latin is a dead language)
'the french can' is the wordplay.
'the french' becomes 'la' (one of the French words for 'the').
'can' becomes 'tin' (both are metal containers).
'la'+'tin'='LATIN'
'get' is the link.
(Other definitions for latin that I've seen before include "The language of Virgil" , "language class" , "Hispanic, for example" , "Old Roman language" , "Language of Cicero" .)