Set aside article carried by upset outcast (6)
I believe the answer is:
repeal
'set aside' is the definition.
(I've seen this before)
'article carried by upset outcast' is the wordplay.
'article' becomes 'a' (indefinite article).
'carried by' means one lot of letters goes inside another.
'upset' is a reversal indicator.
'outcast' becomes 'leper' (leper is a kind of outcast).
'leper' back-to-front is 'repel'.
'a' going inside 'repel' is 'REPEAL'.
(Other definitions for repeal that I've seen before include "'Annul, revoke (6)'" , "Annul a law" , "Annul an act of parliament" , "Cancel or nullify a law" , "Rescind or withdraw a law" .)