One judges cooked rarebit (7)
I believe the answer is:
arbiter
'one judges cooked rarebit' is the definition.
I can't judge whether this definition defines the answer.
'cooked rarebit' is the wordplay.
'cooked' indicates an anagram (letters cooked into a new form).
'rarebit' is an anagram of 'ARBITER'.
Can you help me to learn more?
(Other definitions for arbiter that I've seen before include "Rarebit? (anag)" , "He'll decide" , "One judges a disputed issue" , "Settler of disputes" , "One appointed to settle a dispute" .)