One with deep ground in which body finally buried, watchful (4-4)
I believe the answer is:
open-eyed
'watchful' is the definition.
(I've seen this before)
'one with deep ground in which body finally' is the wordplay.
'with' says to put letters next to each other.
'ground' indicates anagramming the letters ('grind' the letters into a new form).
'in which' is an insertion indicator.
'finally' suggests the final letters.
The last letter of 'body' is 'y'.
'one' put after 'deep' is 'deepone'.
'deepone' with letters rearranged gives 'openeed'.
'openeed' going around 'y' is 'OPEN-EYED'.
'buried' is the link.
This may not be right. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for open-eyed that I've seen before include "Forming an encrusted mass" , "Astonished - watchful" , "Surprised - aware" , "Astonished; fully aware" .)