Auction spilt ales (4)
I believe the answer is:
sale
'auction' is the definition.
(I've seen this before)
'spilt ales' is the wordplay.
'spilt' indicates an anagram.
'ales' is an anagram of 'SALE'.
(Other definitions for sale that I've seen before include "Period of low prices" , "Offer period" , "Clearance of goods at reduced prices" , "Retail event - town in Greater Manchester" , "Occasion for buying at reduced prices" .)