Not as old (7)
'not as old' is the definition.
('young' can be the opposite of 'old' so perhaps 'younger' is reasonable for 'not as old')
This is the entire clue.
(Other definitions for younger that I've seen before include "More juvenile" , "Not so old" , "Less aged" , "Comparatively raw" , "Less mature" .)
'not as old' is the definition.
('new' can be the opposite of 'old' so perhaps 'newer' is reasonable for 'not as old')
This is all the clue.
(Other definitions for newer that I've seen before include "Fresher, not as old" , "More recent" , "More up-to-date" , "More current" , "More modern" .)