Dead, buried in ground, after one's separated (8)
I believe the answer is:
isolated
'separated' is the definition.
(synonyms)
'dead buried in ground after one's' is the wordplay.
'dead' becomes 'late' (similar in meaning).
'buried in' is an insertion indicator (inserted letters get buried).
'ground' becomes 'sod' (both can mean a piece of earth).
'after' says to put letters next to each other.
'one' becomes 'i' (Roman numeral).
'late' placed within 'sod' is 'solated'.
'solated' after 'i' is 'ISOLATED'.
(Other definitions for isolated that I've seen before include "Placed apart from others" , "Off the beaten track" , "Single" , "Without accompaniment" , "Segregated" .)