In-Game Clock

You can toggle between showing the actual time, and the time on this particular puzzle, by tapping on it.

If you want to hide the clock completely (some people prefer to play untimed!) then you can choose to do that from the Settings screen (the cog icon from the title screen.)

Use Prev and Next 

You can use the Prev and Next buttons within the game to cycle round all of the clues. When you get to the end of the list, pressing the button again jumps to the other end so you can continue the cycle.

Delete Whole Words

You can use the backspace button to delete the contents of the currently selected cell, but you can press and hold the delete key to delete out all of the letters you've entered.  Any letters that have been added as a hint or from the magic reveal will stay on, you won't lose those!

Replay Puzzle Packs

If you've completed all of the puzzles in one of the puzzle packs, you can reset it to play them again or for someone else to play through on your device.  Tap and hold the pack icon in the 'Select A Pack' screen, and it will reset for them to all be available again.