Overlooked, but counted in after review (9)
I believe the answer is:
unnoticed
'overlooked' is the definition.
(similar in meaning)
'counted in after review' is the wordplay.
'after review' indicates an anagram (letters reviewed or revised).
'counted'+'in'='countedin'
'countedin' anagrammed gives 'UNNOTICED'.
'but' acts as a link.
(Other definitions for unnoticed that I've seen before include "Not spotted" , "Overlooked" , "behind closed doors?" , "Continued to be not observed" , "Unperceived" .)