One of Waterdeep's many guilds is the Fellowship of Salters, Packers, and Joiners (listed in the introduction of Waterdeep: Dragon Heist, p. 13). What is a joiner in this context?
Merriam-Webster defines a joiner as a craftsperson who joins pieces of wood. Wikipedia has an article on joiners in the same sense.
But Waterdeep already has several guilds related to building things out of wood. It stands to reason that joiners would have some sort of connection to salting and packing food.
Any D&D/Forgotten Realms source is acceptable.