Spoil man eating a daughter's preserve (9)
I believe the answer is:
marmalade
'preserve' is the definition.
(marmalade is a kind of preserve)
'spoil man eating a daughter's' is the wordplay.
'spoil' becomes 'mar' (I've seen this before).
'man' becomes 'male' (**).
'eating' means one lot of letters goes inside another.
'a daughter' becomes 'ad' (I've seen this in other clues).
'male' going around 'ad' is 'malade'.
'mar'+'malade'='MARMALADE'
(Other definitions for marmalade that I've seen before include "Orange preserve" , "Spread" , "Breakfast preserve" , "Preserve made with citrus fruits" , "Sweet food" .)