Gets on
'gets on' is the definition.
(get on can mean to get older)
This is all the clue.
(Other definitions for ages that I've seen before include "Long periods" , "Historical eras" , "Yonks" , "A long time (colloq.)" , "Awfully long time" .)
'gets on' is the definition.
('board' can be a synonym of 'get on')
This is the entire clue.
(Other definitions for boards that I've seen before include "Long flat pieces of wood" , "Puts up" , "Committees or planks" , "Tread them in the theatre" , "Goes on" .)