Cooked up plot to acquire fossil fuel (6)
I believe the answer is:
boiled
'cooked up' is the definition.
(boiling is a type of cooking)
'plot to acquire fossil fuel' is the wordplay.
'plot' becomes 'bed' (a plot of land).
'to acquire' indicates putting letters inside.
'fossil fuel' becomes 'oil' (I've seen this before).
'bed' going around 'oil' is 'BOILED'.
(Other definitions for boiled that I've seen before include "Heated to point at which vapour forms" , "Cooked in hot water" .)