Type of generator (6)
I believe the answer is:
dynamo
'type of generator' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for dynamo that I've seen before include "Generator (sometimes 'human'?)" , "Electricity generator or vigorous person" , "Monday (anag)" , "Electric current generator" , "Tirelessly energetic type" .)