Reject swine involved in racket (6)
I believe the answer is:
'reject' is the definition.
(I know that disown is a kind of reject)
'swine involved in racket' is the wordplay.
'swine' becomes 'sow' (sow is a kind of swine).
'involved in' means one lot of letters goes inside another.
'racket' becomes 'din' (both can mean a loud noise or disturbance).
'sow' placed into 'din' is 'DISOWN'.
(Other definitions for disown that I've seen before include "Refuse to be associated with (a person)" , "Disclaim all connection or relationship with" , "Reject all connection with, refuse to acknowledge" , "Refuse to be associated with (something/someone)" , "Repudiate or refuse to acknowledge a relationship" .)