The Claremont is served at the hotel of the same name, a stately old manse in California’s Bay Area. It’s based on the newfangled, muddled-fruit style of Old-Fashioned-esque cocktails, and uses dry curaçao (Pierre Ferrand, specifically) in place of the usual simple syrup.
You can use a sweeter style of curaçao, like Grand Marnier, but you may wish to pull back on the measure a bit unless you have a sweet tooth. A Caribbean orange shrubb isn’t half bad here, either.