Feat, organising dairy product (4)
I believe the answer is:
feta
'dairy product' is the definition.
'feat organising' is the wordplay.
'organising' indicates anagramming the letters.
'feat' is an anagram of 'FETA'.
(Other definitions for feta that I've seen before include "White Greek cheese" , "White and salty goat or sheep cheese" , "Eastern Mediterranean cheese" , "Greek salad cheese" , "Crumbly Greek cheese" .)