Bidding sale (7)
I believe the answer is:
auction
'bidding sale' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for auction that I've seen before include "Use caution at public sale" , "Public sale to the highest bidder" , "Occasion of lots under the gavel" , "Public sale - type of bridge" , "Selling" .)