Preserve business degree in wooden frame (6)
I believe the answer is:
embalm
'preserve' is the definition.
(as in embalming a body)
'business degree in wooden frame' is the wordplay.
'business degree' becomes 'mba' (Master of Business Administration degree).
'in' means one lot of letters goes inside another.
'wooden frame' becomes 'elm' (elm is a type of wood).
'mba' inserted into 'elm' is 'EMBALM'.
(Other definitions for embalm that I've seen before include "Preserve from decay in death with chemicals" , "Prepare corpse for preservation (6)" , "Preserve body, mummify" , "Use chemicals to preserve a dead body from decay" , "Preserve corpse from decay" .)