Some ordered a mozzarella cheese (4)
I believe the answer is:
edam
'cheese' is the definition.
(I've seen this before)
'some ordered a mozzarella' is the wordplay.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'EDAM' is hidden within 'ordered a mozzarella'.
(Other definitions for edam that I've seen before include "Made into a nice cheese" , "Cheese made badly" , "milk product" , "Kind of cheese" , "Dutch market town famous for its cheese" .)