Make better preserve, perhaps (4)
I believe the answer is:
cure
This clue is a double definition.
'make better' is the first definition.
(as in making a patient better)
'preserve perhaps' is the second definition.
(as in cured meats)
(Other definitions for cure that I've seen before include "Preserve by smoking - make better" , "Foreign priest" , "Make well again" , "Heal or pickle" , "Remedy or preserve" .)