
1) Dregs of cane juice
Found on
https://www.crosswordclues.com/clue/dunder

Dunder is the yeast-rich foam leftovers from one batch of rum that is used to start the yeast culture of a second batch. It is the traditional yeast source in Jamaican rum. Similar in process to sour mash in Bourbon whiskey, it is a crucial step in achieving an authentic rum flavor. Dunder contains many by products that help in future fermentation...
Found on
http://en.wikipedia.org/wiki/Dunder

• (n.) The lees or dregs of cane juice, used in the distillation of rum.
Found on
http://thinkexist.com/dictionary/meaning/dunder/
Dun'der noun [ Confer Spanish
redundar to overflow.] The lees or dregs of cane juice, used in the distillation of rum. [ West Indies] « The use of
dunder in the making of rum answers the purpose of yeast in the fermentation of flour.»
B. Edwards. Found on
http://www.encyclo.co.uk/webster/D/131

the thick lees from boiled sugar-cane juice used in the distillation of rum.
Found on
https://www.infoplease.com/dictionary/dunder
No exact match found.