Okay, if you just clean your aquarium and your tank still smells, I would make sure that you clean the lip around the aquarium.
Make sure you took the tank top off the tank and free it and wipe it down of any food that may have splashed up on it, any waste that may have built up on it. Even bacterial slime could smell. If you didn't replace the carbon in your filter, that could be a reason why your tank smells.
Remember there are odors and impurities just natural, organic waste that's going to have an odor to it. Carbon is the best tool in removing these odors, but after you put fresh carbon in, it could take a day or so to really filter out these waste molecules and these odors so that the tank doesn't smell.
A tank should not smell. I mean, it will always have a slight, like a natural smell to it but it should never be overpowering. You should never be able and close your eyes and guess that there's a fish tank in the room because the odor is so empowering.
If your tank still smells after you've cleaned it, it's probably because you have some waste that went unspotted, or unnoticed, on the underneath of the lid. If you've forgotten and didn't clean the under area around the aquarium, that's a main area that would produce odors. Just make sure you put fresh carbon in there.
I recommend once-a-month you change the carbon resin, either Chemi Pure or activated carbon. Just rinse it first. Most tanks should benefit from using the carbon. Very rarely do you have a tank without carbon where the tank is not yellow and it doesn't smell.
It's just an natural environment. It's going to produce a slight amount of odor. Again, carbon is key to keep those smells in check and keeping your water clean.