Set aside complete boxing record (6)
I believe the answer is:
repeal
'set aside' is the definition.
(I've seen this before)
'complete boxing record' is the wordplay.
'complete' becomes 'real' (I've seen this in another clue).
'boxing' means one lot of letters goes inside another ('box' can mean contain, as in to put in a box).
'record' becomes 'EP' (abbreviation for extended play record).
'real' going around 'ep' is 'REPEAL'.
(Other definitions for repeal that I've seen before include "Withdraw law officially" , "This is what O'Connell wanted" , "reverse" , "Abrogate" , "Annul, rescind" .)