Business graduate lying in wood — prepare for burial (6)
I believe the answer is:
embalm
'prepare for burial' is the definition.
(I've seen this before)
'business graduate lying in wood' is the wordplay.
'business graduate' becomes 'MBA' (Master of Business Administration degree).
'lying in' is an insertion indicator.
'wood' becomes 'elm' (elm is a type of tree).
'mba' going inside 'elm' is 'EMBALM'.
(Other definitions for embalm that I've seen before include "Treat corpse with preservatives" , "Make into mummy" , "Preserve from decay in death with chemicals" , "Treat corpse so as to retard decay" , "Preserve corpse from decay" .)