Decree being horrible, move away (6)
I believe the answer is:
recede
'move away' is the definition.
(synonyms)
'decree being horrible' is the wordplay.
'being horrible' is an anagram indicator.
'decree' is an anagram of 'RECEDE'.
(Other definitions for recede that I've seen before include "Become more distant" , "Move backward" , "Go back, ebb" , "Go backwards" , "Decline" .)