Cancel order I've put out (8)
I believe the answer is:
override
'cancel' is the definition.
(I know that override is a more specific form of the action counteract)
'order i've put out' is the wordplay.
'put out' is an anagram indicator.
'order'+'ive'='orderive'
'orderive' anagrammed gives 'OVERRIDE'.
(Other definitions for override that I've seen before include "Use one's authority to reject or cancel a decision" , "Cancel by higher authority" , "Set aside by superior authority" , "Be more important than" , "Counteract the normal operation" .)