IF s/he is the only bidder cancelling the bid MIGHT bring back the Buy It Now and/or the Best Offer option. But the only listing of yours I see has THREE bidders. If s/he was the first to meet a Reserve Price (which appears to be the case if s/he is the bidder leading at $1200) it is likely that the BIN will return but you would not be able to change the BIN amount (the Best Offer would not come back). If you are willing to sell to him/her for the $1200 you can end the auction early and choose the option to sell to the high bidder at the current bid amoun.
It is usually not in the seller's best interest to accept such unsolicited offers. They are frequently made by scammers but even at best are made because the offeror a) doubts that the amount would win if the auction goes to the end and/or b) is 1) chronically and/or 2) situationally impatient. To accept it if none of the above works you have to cancel all bids and end the listing early without a winner (ticking off your existing and prospective bidders and incurring an extra fee) and then relist the item in a manner that allows the offeror to buy it properly at the correct price, with no guarantee that s/he will do so (it is likely s/he has made multiple such offers).
