A groat was a Cardassian foodstuff that, among other things, serves 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")
"Groat clusters" first appeared in the 1970 Firesign Theatre album "Don't Crush That Dwarf, Hand Me The Pliers."