Noble individuals look mature (7)
I believe the answer is:
peerage
'noble individuals look mature' is the definition.
I can't tell whether this definition defines the answer.
'look mature' is the wordplay.
'look' becomes 'peer' (peering is a kind of looking).
'mature' becomes 'age' (synonyms).
'peer'+'age'='PEERAGE'
Can you help me to learn more?
(Other definitions for peerage that I've seen before include "Dukes, earls, lords, ladies - the lot" , "Ranks of the nobility" , "Nobles collectively" , "Lordly group" , "Book of the nobility" .)