Energetic sort has Monday off (6)
I believe the answer is:
dynamo
'energetic sort' is the definition.
(I've seen this in another clue)
'monday off' is the wordplay.
'off' indicates anagramming the letters.
'monday' anagrammed gives 'DYNAMO'.
'has' is the link.
(Other definitions for dynamo that I've seen before include "Generator of electricity on Monday" , "One creating electricity" , "Producer of electrical energy" , "Energy converter - hard worker" , "Generator (sometimes 'human'?)" .)