Paper round, flipping burden! (4)
I believe the answer is:
onus
'burden' is the definition.
(I know that burden can be written as onus)
'paper round flipping' is the wordplay.
'paper' becomes 'sun' (The Sun, UK newspaper).
'round' becomes 'o' (o is a circular letter).
'flipping' says the letters should be written backwards.
'sun'+'o'='suno'
'suno' reversed gives 'ONUS'.
(Other definitions for onus that I've seen before include "Liability" , "Encumbrance" , "albatross?" , "'Burden, of proof (4)'" , "Weight of responsibility" .)