Wrongly ordered all the killing (6)
I believe the answer is:
lethal
'killing' is the definition.
(thesaurus)
'wrongly ordered all the' is the wordplay.
'wrongly ordered' indicates an anagram (I've seen this in other clues).
'all'+'the'='allthe'
'allthe' anagrammed gives 'LETHAL'.
(Other definitions for lethal that I've seen before include "bringing down the curtain" , "Terminal" , "All the change can be deadly." , "Deadly, potentially fatal" , "Death-dealing" .)