Democrat with base and evil scheme (6)
I believe the answer is:
device
'scheme' is the definition.
(device can mean a scheme or method)
'democrat with base and evil' is the wordplay.
'democrat' becomes 'd'.
'with' says to put letters next to each other.
'base' becomes 'e' (Euler's number - base of natural logarithms).
'and' means one lot of letters go next to another.
'evil' becomes 'vice' (vice is a kind of evil).
'd'+'e'+'vice'='DEVICE'
(Other definitions for device that I've seen before include "Scheme, trick; item of equipment" , "Instrument made for a special purpose" , "Instrument made for a specific purpose" , "Appliance, gadget" , "Plan, scheme, trick" .)