I don't have the rule book near me and I now always have delay clocks on tourneys I run so haven't really worried about the rule that much. However, it isn't that you are clearly winning in such a situation but that you can't lose. The rule is Insufficient Losing Chances and it can't be invoked in if a delay is in effect.
If the game doesn't have a delay and you have 2 minutes or less on the clock you can claim a draw based on insufficient losing chances.
- If the TD agrees with you, you get the draw.
- If the TD doesn't agree, the game continues and there may be a penalty (adding some time to the opponent's clock maybe)
- If the TD is unsure then the option is to either let the game continue and try to resolve the claim, based on play (is the opponent trying to win, or just shuffling pieces to win on time)
- Alternatively, place a delay clock. One of the references online states the claimant loses half their time in that case, the opponent keeps all theirs. I believe in such a case, that you can still lose on time but the delay clock should be sufficient to let the TD know if the opponent is trying to make progress or if you will obviously prove the draw, either directly on the board or via triple repetition of position or 50 moves.
In any cases, a draw claim is also a draw offer.
I was told that you can call on Tournament Director to declare your game a draw when "clearly winning" but Low on time and opponent has insufficient materials. Or, TD can issue a digital clock and players are given 5 seconds to move. In this case, the play resumes and cannot lose on time...???