Cheese is component of buffet always (4)
I believe the answer is:
feta
'cheese' is the definition.
(type of cheese)
'component of buffet always' is the wordplay.
'component of' says the answer is hidden in the clue (I've seen this in other clues).
'FETA' can be found hidden inside 'buffet always'.
'is' acts as a link.
(Other definitions for feta that I've seen before include "Greek dairy product" , "Soft Greek cheese" , "Salty Greek cheese" , "Goat's or sheep's milk cheese" , "Type of cheese" .)