Deb I'd really be at a loss on that one except for a wild guess or two. For one thing, my DIY abilities are vastly limited by the fact that some years ago I totally lost my
sense of smell due to (apparently) permanent nerve damage. For another, I no longer imbibe so I'd have to rely upon your (or someone else's) tasting & direction. I will ask you this though: have you ever tried Drambuie on the rocks with just a splash of your favorite 12-yr old Single Malt? (Quantities may be adjusted to taste, of course.) Not exactly a Rusty Nail... I think of it more as a Golden Peg. But anyway if memory (which, in cruel irony, is closely related to the sense of smell) serves, I'm thinking to shoot for a Drambuie
juice you might want to start with a Single Malt Scotch flavoring & work from there. Honey maybe? I dunno. Used to love that stuff but probably haven't tasted any in over 30 years.
Anyway if you find any let me know, & Happy Hunting!