Generator (6)
'generator' is the definition.
(dynamo is a kind of generator)
This is all the clue.
(Other definitions for dynamo that I've seen before include "Type of electrical generator" , "Electricity generator or vigorous person" , "Energy converter - hard worker" , "Generator of electricity (eg, on bicycle)" , "Generator of electricity on Monday" .)
(Other definitions for cope that I've seen before include "Join" , "Manage, come to terms with" , "Episcopal cloak" , "Handle a situation" , "Deal with, manage successfully" .)
'generator' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for reactor that I've seen before include "Nuclear energy generator" , "See 3 Down" , "chemical substance!" , "Creator (anag.)" , "(Nuclear) powerplant" .)