The first thing to check is the strainer over the drain. Remove it, look for any food or gunk, then clean it off thoroughly to make sure it isn’t causing your clog.
Next, use a plunger. Partially fill the sink with water (if it isn’t already filled), then work the plunger down and up several times before quickly pulling it off the drain opening. If you have a double-bowl kitchen sink, stuff a wet rag into the drain opening that isn’t clogged (this will help with suction).
Finally, try Drano® Dual-Force® Foamer Clog Remover if your sink has a garbage disposal—it pours through standing water and attacks clogs directly at the source. Remember to use Drano® Professional Strength Crystals Clog Remover if the sink does not have a disposal. It creates heat inside your drain to melt and dislodge greasy clogs.
And consider keeping some Drano® clog remover on hand just in case. No one wants to make a trip to the store in the middle of a kitchen sink crisis!