at a given price of a commodity, there is 'excess supply'. is this an equilibrium price ? if not how will the equilibrium price be reached ? use diagram..

No, this is not equilibrium price as at supply is not equal to demand at this price. The diagram and explanation for 'Excess supply' is already covered in our study material. Follow the given link and scroll down to the topic ' Increase in market supply' to view the same.

https://www.meritnation.com/cbse/class12-commerce/studymaterial/economics/introductory-microeconomics/market-equilibrium/338_1984_5822#slide2_market-equilibrium-under-fixed-number-of-firms