Cremated? Ashes vase placed in garden plot (6)
I believe the answer is:
burned
'cremated?' is the definition.
(cremating is a kind of burning)
'ashes vase placed in garden plot' is the wordplay.
'ashes vase' becomes 'urn' (I've seen this before).
'placed in' indicates putting letters inside (I've seen this in other clues).
'garden plot' becomes 'bed' (I've seen this in another clue).
'urn' put within 'bed' is 'BURNED'.
(Other definitions for burned that I've seen before include "Set fire to" , "Blazed" .)