Language of a quarter of Parisians (5)
I believe the answer is:
latin
I believe this clue is a double definition.
'language' is the first definition.
(Latin is an example)
'a quarter of parisians' is the second definition.
(I've seen this before)
'of' acts as a link.
(Other definitions for latin that I've seen before include "Shakespeare's was small, according to Jonson" , "Ancestor of French, Romanian" , "Language of ancient Rome" , "A Romance language" , "difficult subject" .)