College ceremony ends early for one key judge (6)
I believe the answer is:
Here is my best explanation:
'judge' is the definition.
(critic is a kind of judge)
'college ceremony ends early for one key' is the wordplay.
'college' becomes 'c'.
'ceremony' becomes 'rite' (rite is a kind of ceremony).
'ends early' means to remove the last letter (I've seen 'ending early' mean this).
'for' is a charade indicator (letters next to each other).
'one key' becomes 'ic' (I can't justify this - if you can you should give a lot more credence to this answer).
'rite' with its final letter taken off is 'rit'.
(Other definitions for critic that I've seen before include "Commentator, pundit", "(Eg, theatre) reviewer", "Evaluator, reviewer", "Professional reviewer of literature, art, drama or music", "One analyses and interprets works of art", "A reviewer of plays, books etc", "Person who reviews plays, films etc", "One judges the merit of artistic works", "One who assesses" and "Performance judge".)