A French setting, we hear, in text for translation (6)
I believe the answer is:
unseen
'text for translation' is the definition.
(in exams, a piece of text not previously seen)
'a french setting we hear' is the wordplay.
'a french' becomes 'un' ('a' in French).
'setting' becomes 'scene' (I've seen this before).
'we hear' shows a homophone (sound like).
'scene' sounds like 'seen'.
'un'+'seen'='UNSEEN'
'in' acts as a link.
(Other definitions for unseen that I've seen before include "Translation exercise" , "Not perceived or observed" , "not exercising pupils?" , "Invisible or not observed" , "not processed by pupils?" .)