persistently ask for overdue payment(verb.communication)
Example: The grocer dunned his customers every day by telephone.
source: wordnet30
cure by salting(verb.change)
Example: Dun codfish.
source: wordnet30
make a dun color(verb.change)
source: wordnet30
To cure, as codfish, in a particular manner, by laying them, after salting, in a pile in a dark place, covered with salt grass or some like substance.(verb)
source: webster1913
To ask or beset, as a debtor, for payment; to urge importunately.(verb)