Blame for spilling marmalade, just having opened preserve (6)
I believe the answer is:
embalm
'preserve' is the definition.
(embalming is a kind of preserving)
'blame for spilling marmalade just having opened' is the wordplay.
'for spilling' is an anagram indicator (spilling can mean chaos or upset).
'just having opened' suggests taking the first letters (only the opening letter is used).
The initial letter of 'marmalade' is 'm'.
'blame' with letters rearranged gives 'embal'.
'embal'+'m'='EMBALM'
(Other definitions for embalm that I've seen before include "Treat corpse so as to retard decay" , "Preserve from decay in death with chemicals" , "Prepare corpse for preservation (6)" , "Treat corpse with preservatives" , "Make into mummy" .)