Born not so long ago (7)
I believe the answer is:
younger
'so long ago' is the definition.
I can't judge whether this defines the answer.
'born not' is the wordplay.
I cannot quite understand how this works, but
'born' could be 'n' (abbreviation, from the French 'nee') and 'n' is found in the answer.
'not' could be 'o' (I've seen this in other clues) and 'o' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for younger that I've seen before include "Less experienced" , "Seven PM" , "More youthful" , "Not so old" , "Less mature" .)