Dairy product affected fate (4)
I believe the answer is:
feta
'dairy product' is the definition.
(type of cheese)
'affected fate' is the wordplay.
'affected' indicates anagramming the letters.
'fate' is an anagram of 'FETA'.
(Other definitions for feta that I've seen before include "Eastern Mediterranean cheese" , "10 down cheese" , "Low-fat cheese" , "Salty goat or sheep milk cheese" , "Greek salad cheese" .)