Again share out genuine sale item (7)
I believe the answer is:
reallot
'again share out' is the definition.
('allot' can be a synonym for 'share out' so perhaps 'reallot' is OK for 'again share out')
'genuine sale item' is the wordplay.
'genuine' becomes 'real' (associated in meaning).
'sale item' becomes 'lot' (item for sale at auction).
'real'+'lot'='REALLOT'
(Other definitions for reallot that I've seen before include "share out again" , "set aside again" , "Once again divide out" , "Parcel out again" , "Distribute again" .)