Idiot about item in auction (4)
I believe the answer is:
clot
'idiot' is the definition.
(both can mean a stupid person)
'about item in auction' is the wordplay.
'about' becomes 'c' (circa).
'item in auction' becomes 'lot' (I've seen this before).
'c'+'lot'='CLOT'
(Other definitions for clot that I've seen before include "Mass of material" , "Clumsy person" , "Fool; solidified blood" , "A lump in a blood vessel" , "Coagulate - fool" .)