Many do upset supplier of power (6)
I believe the answer is:
dynamo
'supplier of power' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'many do upset' is the wordplay.
'upset' indicates anagramming the letters.
'many'+'do'='manydo'
'manydo' anagrammed gives 'DYNAMO'.
Can you help me to learn more?
(Other definitions for dynamo that I've seen before include "Device producing electrical power" , "Electricity generator or energetic person" , "Tirelessly energetic type" , "Juice supplier" , "Small generator" .)