Advanced in years (4)
(Other definitions for aged that I've seen before include "not a modern copy" , "Senior" , "Became older" , "Got older" , "Grew old" .)
'advanced in years' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for elderly that I've seen before include "Fairly old, past middle age" , "Rather old" , "Silver" , "Getting on in years" , "over the hill" .)