Responsibility (4)
'responsibility' is the definition.
(I know that responsibility can be written as duty)
This is all the clue.
(Other definitions for duty that I've seen before include "Is one bound" , "Cancel (a law)" , "A tax; compulsory task" , "Moral/legal obligation" , "Not subject to customs tax" .)
'responsibility' is the definition.
(onus is a duty or responsibility)
This is all the clue.
(Other definitions for onus that I've seen before include "Capulet opponent (R&J)" , "Responsibilty" , "Obligation - charge" , "'Burden, of proof (4)'" , "Liability" .)
'responsibility' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for burden that I've seen before include "Oppressive duty" , "Onerous or difficult load" , "Unwelcome load" , "chorus" , "Weigh down - load" .)