The only thing that makes this drink a holiday cocktail is its name. The Under the Mistletoe has aged rum, apricot liqueur, lime juice, and bitters. Angostura bitters contain some winter spice flavors, but that's about as close as we get.
The recipe comes to us from Lexington Social House, which is not in Lexington, Kentucky but Los Angeles, California. So perhaps the lack of winter there helps explain the confusion.
Under the Mistletoe
Adapted from a recipe by Lexington Social House
1.5 fl. oz. Mount Gay Aged Rum
.75 fl. oz. Rothman & Winter Apricot Liqueur
1 fl. oz. Fresh Lime Juice
2 dashes Angostura Bitters
Mint Sprig for Garnish
Shake all ingredients with ice and dump all into a Collins glass. Garnish with a sprig of mint.