One theologian upset eating old Cypriot cheese (8)
I believe the answer is:
halloumi
'cypriot cheese' is the definition.
(I've seen this before)
'one theologian upset eating old' is the wordplay.
'one' becomes 'i' (Roman numeral).
'theologian' becomes 'mullah' (I am not sure about this - if you are sure you should believe this answer much more).
'upset' says the letters should be written in reverse.
'eating' indicates putting letters inside.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'i'+'mullah'='imullah'
'imullah' backwards is 'hallumi'.
'hallumi' going around 'o' is 'HALLOUMI'.
Can you help me to learn more?
(Other definitions for halloumi that I've seen before include "Traditional Cypriot cheese" , "Cheese from Cyprus" , "Cypriot goat's or sheep's milk cheese" , "Greek dish of fried goat's cheese" .)