After not much revision, came top (4)
I believe the answer is:
acme
'top' is the definition.
(synonyms)
'after not much revision came' is the wordplay.
'after not much revision' indicates an anagram (a simple anagram with only one letter moving).
'came' with letters rearranged gives 'ACME'.
(Other definitions for acme that I've seen before include "Zenith - optimum" , "Summit of achievement" , "Highest level or degree attainable" , "Summit - maximum" , "crisis in history" .)