In French earth, duke is buried (8)
I believe the answer is:
interred
'is buried' is the definition.
('interred' can be a synonym of 'buried')
'in french earth duke' is the wordplay.
'french earth' becomes 'terre' ('earth' in French).
'duke' becomes 'd'.
'in'+'terre'+'d'='INTERRED'
(Other definitions for interred that I've seen before include "Trendier way to be buried" , "Placed in a grave" , "stuck in ground" .)