Deny order was void (7)
I believe the answer is:
disavow
'deny' is the definition.
(disavowing is a kind of denying)
'order was void' is the wordplay.
'order' is an anagram indicator.
'was'+'void'='wasvoid'
'wasvoid' with letters rearranged gives 'DISAVOW'.
(Other definitions for disavow that I've seen before include "Refuse to acknowledge" , "Deny responsibility for (something)" , "To deny support" , "Disclaim" , "To deny knowledge of" .)