Commoner, English, in biplane flying (8)
I believe the answer is:
plebeian
'commoner' is the definition.
(plebeian is a kind of commoner)
'english in biplane flying' is the wordplay.
'english' becomes 'e' (abbreviation).
'in' is an insertion indicator.
'flying' indicates anagramming the letters.
'biplane' is an anagram of 'plebian'.
'e' going into 'plebian' is 'PLEBEIAN'.
(Other definitions for plebeian that I've seen before include "Of the lower social classes, or uncultured" , "Lower-class; commoner" , "Non-U?" , "not refined" , "Common person" .)