Extremes of exploitation editor gleefully used to demonstrate power (6)
I believe the answer is:
energy
'power' is the definition.
(synonyms)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for energy that I've seen before include "Vigour, spirit" , "Vivacity" , "It's measured in joules or ergs" , "Vigour, animation" , "'Vigour, vitality (6)'" .)