The wording for this achievement is a bit off. The actual requirements for this is to get the best SINGLE score of the hour.
By far the easiest way to do this is to change the puzzle language to Arabic and systematically work through the puzzle trying to get as many words as you can.
To find out where you are on the leaderboard go to:
Leaderboards > Best Of > Then select the drop down box and change it to Best of the Hour.
If you have just got a really high score but it hasn't put it on the leaderboard yet, Don't Worry!! just play or wait through another game and after that the boards should have updated and if you are top you should get your achievement.
Should you not unlock your achievement straight away, just close down the app and load it back up again and if you were 1st of the hour at any point, your achievement should pop.
If you have managed to get your achievement on Windows 8 or Windows Phone, then to get the achievement on the other platform all you have to do is load up the game on the version you haven't got the achievement for yet and it should unlock straight away, without even having to play a game.
EDIT- If you have managed to get high score which meant you were 1st on the iOS version, then you will get the achievement when you log on to the other versions. Credit to Fadi kun.