Mastermind in Greene running riot (8)
I believe the answer is:
engineer
'mastermind' is the definition.
(both can mean to contrive or plot something)
'in greene running riot' is the wordplay.
'in' indicates putting letters inside.
'running' indicates an anagram (the letters run around to different places).
'riot' becomes 'in' (I am not sure about this - if you are sure you should believe this answer much more).
'greene' anagrammed gives 'engeer'.
'engeer' going around 'in' is 'ENGINEER'.
Can you help me to learn more?
(Other definitions for engineer that I've seen before include "Plot" , "One uses scientific knowledge to solve practical problems" , "Professional who may be civic, electrical or mechanical" , "Skilled professional - electrical, civil or mechanical" , "One uses science to solve practical problems" .)