Shieldaig (in the States) is a line of mystery malts and blends bottled for the Total Wine chain by Ian Macleod (an independent bottler and owner of Glengoyne and Tamdhu). While you will find plenty of speculation where this single malt is sourced from, it's probably fruitless as sources may change and the profile is unlikely to match up with official named malts.
This whisky was bottled at 40%, probably with coloring and chill filtration.
Shieldaig Speyside 18 Year
Nose: initially very muted and blend-y - eventually sherry, oak, baking spices, herbal/green, vanilla, floral, cardboard malt, bubblegum. After adding a few drops of water a lot of honey and oatmeal come out, the oak becomes buttery, but it reads as more youthful and with less sherry.
Taste: sherry sweetness throughout, apple/pear in the background around the middle, fading into bittersweet malt near the back. After dilution it becomes sweeter up front, with honey and malt overtaking the sherry, which comes back around the middle and joins more identifiable oak near the back.
Finish: sherry, oak residue, clean malt
While not the most exciting malt, I think it accomplishes its intended task fairly well. Most buyers are going to pick it because of the age on the label and want something relatively easy drinking and unchallenging. I feel like it does a decent job competing with basic 18 year old malts from the likes of Glenfiddich and Glenlivet, but without the heavy oak component found in those that give them a sense of age. Given that it costs significantly less than the direct competition, these trade-offs seem perfectly acceptable. It loses some points for having some cardboard notes that I associate with tired casks, but that's kind of what you get at the price. While it doesn't have any caché like a malt from an identifiable distillery, once it's in the glass it does a very competent job.