Stop -- proceed after amber changes (7)
I believe the answer is:
embargo
'stop' is the definition.
(embargoing is a kind of stopping)
'proceed after amber changes' is the wordplay.
'proceed' becomes 'go' ('go' can be a synonym of 'proceed').
'after' says to put letters next to each other.
'changes' is an anagram indicator.
'amber' with letters rearranged gives 'embar'.
'go' after 'embar' is 'EMBARGO'.
(Other definitions for embargo that I've seen before include "Admiralty order" , "restrict trade" , "Restraint - prohibition" , "Stop" , "Government order imposing a trade barrier" .)