calf
犢 centers on a young bovine: a calf. The meaning is specific to a young cow or ox.
犢 combines 牜 (cow) with 賣, which likely contributes the sound トク. The character specifically denotes a calf.
The left side 牜 is a cow, and the right side 賣 looks like a complicated market stall. Picture a young calf being sold at a market: 犢 is a calf.
For トク, imagine a calf with a distinctive toque (a chef's hat) on its head: toque -> トク, and the calf wears it proudly.