Decree that Dorian has become corrupted (6)
I believe the answer is:
ordain
'decree' is the definition.
(I know that ordain is a more specific form of the action decree)
'dorian has become corrupted' is the wordplay.
'dorian' can be anagrammed to 'ORDAIN'.
But, I am unsure how the anagram is indicated.
'that' is the link.
Can you help me to learn more?
(Other definitions for ordain that I've seen before include "Elevate or appoint to priesthood" , "Consecrate as priest" , "Appoint - admit to holy orders" , "Appoint as priest" , "frock" .)