This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
驝 combines 馬 (horse) with 槖, but the exact historical development and original meaning are uncertain.
The left side is a horse 馬, and the right side 槖 looks like a bundle or sack. Picture a horse carrying a mysterious bundle, but its purpose is unclear.
For タク, imagine a horse pulling a tack (thumbtack) out of the bundle: tack -> タク, though the meaning remains uncertain.