Are you running any type of carbon ?
If you use an external with a carbon pad, replace with a good quality carbon. This will also help clear up the water and help maintain the tank clear and free of fishiers smells.
Carbon though is always the topic of debate with most hobbiest.
Some prefer NOT to use it. And others like myself swear by it. Now, NOT all carbon is the same. there are many brands and not all work the same. the cheaper brands IMO / IME do not perform as the better / name brands. whisper,penguin,aquarium pharm, dimond are all good quality carbons and IMO / IME help maintain a clear tank and helps clear up a cloudy tank.
Stay away from all those tank clear additives.
DO NOT use additives to try and rid this problem. try to avoid water change till tank clears. If you start to do partial changes before it clears it can / will take longer because now the bacteria has to re-establish.
But, as Rose mentioned, best way to treat cloudy tank, Time......... and some good carbon.
Danny