I ranted about item given in part-payment (5-2)
I believe the answer is:
trade-in
'item given in part-payment' is the definition.
(an item traded in)
'i ranted about' is the wordplay.
'about' indicates anagramming the letters.
'i'+'ranted'='iranted'
'iranted' with letters rearranged gives 'TRADE-IN'.
(Other definitions for trade-in that I've seen before include "Older article used in part payment to retailer" , "Trained (anag.)" , "Article used in part-exchange" , "I daren't (anag)" , "Article used in part payment for another" .)