Overlooked doing RE revision (7)
I believe the answer is:
ignored
'overlooked' is the definition.
(I've seen this before)
'doing re revision' is the wordplay.
'revision' indicates anagramming the letters.
'doing'+'re'='doingre'
'doingre' anagrammed gives 'IGNORED'.
(Other definitions for ignored that I've seen before include "Cut" , "Failed to notice" , "Disregarded intentionally; failed to consider" , "Passed over" , "Paid no attention to" .)