Most fullscreen apps, (majority of games and video player/streaming apps), are programmed to hide the Status Bar. So, it is not possible by any means to have the clock continuously displayed while playing the game/video.
Since you are concerned about losing the grip of the device and do not want to move your hand much (to perform the swipe down gesture), there's an alternate approach you can take. Without moving your hands and pausing the game, simply press the power button of the device to put it in sleep mode. The game/video will be paused automatically.
Now, quickly press the Home button (without unlocking the device) to show the lock screen which will also display the time. Now, use Touch ID to unlock the iPad and un-pause to resume playing the game/video. (This approach is assuming that you have enabled Touch ID to unlock your iPad. The goal here is to wake the device without unlocking it. Act accordingly if you do not use Touch ID to unlock your iPad.)
The aforementioned can be performed (in most cases) without losing the grip of the device. Works best in landscape orientation (and with large hands 😀). I too take this approach when playing games on iPad.