A valet was a servant who acted as an assistant.
Following Xelo, Mr. Homn served as valet to Lwaxana Troi. (TNG: "Haven") He did not share her quarters. (TNG: "Half a Life")
Mona Luvsitt was Julian Bashir's "personal valet" in his secret agent holo-program. Her services were provided by the government. (DS9: "Our Man Bashir")