A groat was a Cardassian foodstuff that, among other things, served as the base for groatcakes. (DS9: "The Magnificent Ferengi")

Odo once remarked of Ferengi that they would sell their own flesh and blood for a Cardassian groat. (DS9: "Necessary Evil")

In 2374, Quark came to Odo's office to speak with him about a missing shipment of groat clusters. (DS9: "His Way")

"Groats" and "Groat Clusters" are terms taken from the 1970 comedy album "Don't Crush That Dwarf, Hand Me The Pliers" by the American comedy troupe The Firesign Theater.
According to the Star Trek Encyclopedia (4th ed., vol. 1, p. 319), groat was the "grain of a cereal grass widely cultivated on Bajor and providing a flour for baked goods such as bread and pastries."