Cheese served up for tea — not yellow (4)
I believe the answer is:
feta
'cheese' is the definition.
(I've seen this before)
'up for tea not yellow' is the wordplay.
'up' is an anagram indicator.
'not' indicates named letters should be taken away.
'yellow' becomes 'or' (heraldic term).
'for'+'tea'='fortea'
'fortea' with 'or' taken out is 'ftea'.
'ftea' anagrammed gives 'FETA'.
'served' is the link.
(Other definitions for feta that I've seen before include "Salty Greek cheese" , "Greek sheep or goats' cheese" , "Greek cheese from goat or sheep milk" , "10 down cheese" , "Crumbly Greek cheese" .)