Completely out of order (4)
I believe the answer is:
dead
This clue could be a double definition.
'completely' is the first definition.
(synonyms)
'out of order' is the second definition.
'dead' can be an answer for 'out' (thesaurus). I am not sure about the 'of order' bit.
Can you help me to learn more?
(Other definitions for dead that I've seen before include "As was Monty Python's parrot" , "Absolutely" , "directly" , "Late; exact" , "no longer with us" .)