Onus (6)
'onus' is the definition.
(synonyms)
This is all the clue.
(Other definitions for burden that I've seen before include "chorus" , "Main theme (of book)" , "Oppressive duty" , "A heavy load or difficulty" , "Onerous or difficult load" .)
'onus' is the definition.
(synonyms)
This is all the clue.
(Other definitions for encumbrance that I've seen before include "drag" , "confounded nuisance!" , "liability" , "Impediment - burden" .)