Grey or white-haired (5)
I believe the answer is:
hoary
I believe this is a double definition.
'grey' is the first definition.
(I know that grey can be written as hoary)
'white-haired' is the second definition.
(thesaurus)
(Other definitions for hoary that I've seen before include "Of joke, old and much-heard" , "Like an old joke" , "Grey haired; old (joke)" , "White or grey, or old as of joke" , "Grey-haired and old" .)