Never seeming to get older or younger? (7)
I believe the answer is:
ageless
'never seeming to' is the definition.
I can't tell whether this defines the answer.
'get older or younger?' is the wordplay.
I cannot quite understand how this works, but
'younger?' could be 'less' and 'less' is found within the answer.
'get older' could be 'age' (synonyms) and 'age' is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for ageless that I've seen before include "not appearing to get old" , "Never growing old" , "Staying young" , "Ever young" , "Lasting a long time" .)