Common person that is to be back in scheme (8)
I believe the answer is:
plebeian
'common person' is the definition.
(plebeian is a kind of common person)
'that is to be back in scheme' is the wordplay.
'that is' becomes 'ie' ('i.e.' can be a synonym of 'that is').
'to' is a charade indicator (letters next to each other).
'back' shows that the letters should be reversed in order.
'in' means one lot of letters goes inside another.
'scheme' becomes 'plan' (I've seen this before).
'ie'+'be'='iebe'
'iebe' written backwards gives 'ebei'.
'ebei' going into 'plan' is 'PLEBEIAN'.
(Other definitions for plebeian that I've seen before include "Lower-class; commoner" , "Of the lower social classes, or uncultured" , "Of the lower social classes, as in ancient Rome" , "Non-U?" , "Lacking in refinement" .)