Academic researcher's job, as before, essentially sucks (7)
I believe the answer is:
postdoc
'academic researcher's' is the definition.
'job as before essentially sucks' is the wordplay.
'job' becomes 'post' (post is a kind of job).
'as before' becomes 'do' (I've seen this in other clues).
'essentially' indicates the central letters.
The middle letter of 'sucks' is 'c'.
'post'+'do'+'c'='POSTDOC'
(Other definitions for postdoc that I've seen before include "Someone doing advanced research" , "Researcher" .)