Auction action
'auction action' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for bid that I've seen before include "Make offer for 20 Down" , "Offer a sum of money to buy" , "Make an offer at auction" , "Order - offer" , "Propose a payment" .)
(Another definition for opening bid that I've seen is " Such as 1D".)