Hard worker turning in too many drafts (6)
I believe the answer is:
dynamo
'hard worker' is the definition.
(I've seen this in another clue)
'turning in too many drafts' is the wordplay.
'turning' says the letters should be written in reverse.
'in' indicates the answer is hidden within the clue.
'omanyd' is hidden in the letters of 'too many drafts'.
'omanyd' back-to-front is 'DYNAMO'.
(Other definitions for dynamo that I've seen before include "Electricity generator or energetic person" , "Generator of electricity on Monday" , "Juice supplier" , "Type of electrical generator" , "Power source" .)