The responsibility we bear (4)
I believe the answer is:
onus
I believe this clue is a double definition.
'the responsibility' is the first definition.
(onus is a duty or responsibility)
'we bear?' is the second definition.
(we carry anything on us)
(Other definitions for onus that I've seen before include "Obligation - charge" , "Weight of responsibility" , "'Responsibility, task or burden (4)'" , "'Burden, of proof (4)'" , "Responsibilty" .)