Remember to cancel (6)
I believe the answer is:
recall
This clue is a double definition.
'remember' is the first definition.
('recall' can be a synonym of 'remember')
'cancel' is the second definition.
(recalling is a kind of cancelling)
'to' is the link.
(Other definitions for recall that I've seen before include "Evoke" , "Order to return" , "cancel" , "Summon back, perhaps to mind" , "order to come back" .)