try bicarbonate and vinegar, pour bicarbonate in a small plastic bottle. Add vinegar and hold you finger on the top otherwise it will spill. Turn the bottle upside down, just above your clog, remove your finger and at the same time squeeze the bottle as hard as you can to get those bubbles in there with force/ Normally that does the trick.
You can try vinegar and baking soda, but if it is really clogged you are going to have to snake it out. Home Depot sells a snake that you attach to your drill and works really well if you do not want to call a plumber.
This product works best for removing common things which clog a tub. https://amzn.to/2YCOLjF
How to Unclog a Bathtub Drain Using Baking Soda and Vinegar
Pour baking soda down the drain. Then pour some vinegar. Let it foam up. Then pour hot water down. If it's still clogged you may need to rod it.