Responsibility — and where ours falls (4)
I believe the answer is:
onus
'responsibility' is the definition.
(onus is a duty or responsibility)
'and where ours falls' is the wordplay.
I cannot really see how this works, but
'and' could be 'n' (common abbreviation for 'and') and 'n' is present in the answer.
The remaining letters 'ous' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for onus that I've seen before include "'Responsibility, task or burden (4)'" , "Encumbrance" , "albatross?" , "Duty or responsibility" , "'Burden, load (4)'" .)