The rotter upset tea on a cleric! (6)
I believe the answer is:
curate
'a cleric' is the definition.
(I've seen this before)
'the rotter upset tea' is the wordplay.
'the rotter' becomes 'cur' (I can't explain this - if you can you should believe this answer much more).
'upset' indicates an anagram.
'tea' anagrammed gives 'ate'.
'cur'+'ate'='CURATE'
'on' is the link.
Can you help me to learn more?
(Other definitions for curate that I've seen before include "Acuter (anag.)" , "Minister of religion" , "He didn't really want an egg" , "look after collection" , "His egg is said to be good in parts." .)