Familiar with (4,2)
'familiar with' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for used to that I've seen before include "Did at times in the past" , "Familiar with" , "Was in the habit" , "Not unfamiliar with" , "Accustomed or inured" .)
(Another definition for wise to that I've seen is " Knowing".)
(Another definition for athome that I've seen is " reception".)