Going back again through, I left out "productive" (7)
I believe the answer is:
fertile
'productive' is the definition.
('fertile' can be a synonym of 'productive')
'going back again through i left out' is the wordplay.
'going back' is a reversal indicator.
'again' becomes 're'.
'through' means one lot of letters goes inside another (I've seen this in other clues).
'out' is an anagram indicator (out can mean wrong or inaccurate).
're' written backwards gives 'er'.
'i'+'left'='ileft'
'ileft' is an anagram of 'ftile'.
'er' inserted inside 'ftile' is 'FERTILE'.
(Other definitions for fertile that I've seen before include "(Of soil) richly productive" , "Let rife (anag)" , "Abundantly productive" , "Able to reproduce abundantly" , "Producing good crops" .)