Scheme includes one not so much like a drone (9)
I believe the answer is:
pilotless
'drone' is the definition.
(I've seen this before)
'scheme includes one not so much' is the wordplay.
'scheme' becomes 'plot' (plot is a kind of scheme).
'includes' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'not so much' becomes 'less' (I've seen this before).
'plot' going around 'i' is 'pilot'.
'pilot'+'less'='PILOTLESS'
'like a' acts as a link.
(Other definitions for pilotless that I've seen before include "drone" , "Lacking a navigator" .)