Trading Property to settle a debt in Monopoly
What's unclear about the rules:


  You are declared bankrupt if you owe more than you
  can pay either to another player or to the Bank. ....
  
  ... A bankrupt player must immediately retire from the
  game. The last player left in the game wins.


Unless one can find a way to clear the entire debt while retaining an asset of at least $1 value, thus avoiding bankruptcy, the bankrupt player is out of the game; just as the rule stipulates.

Part of the beauty of the game is the simplicity of the rules as written. Imagining considerations that are not actually in the rules is what leads to games dragging on for hours; I for one would rather concede a lost game and get started on a second.