Son, mature and wise (4)
I believe the answer is:
sage
'wise' is the definition.
('sage' can be similar in meaning to 'wise')
'son mature' is the wordplay.
'son' becomes 's'.
'mature' becomes 'age' ('age' can be a synonym of 'mature'**).
's'+'age'='SAGE'
'and' is the link.
(Other definitions for sage that I've seen before include "Herb used in cooking" , "Wise woman" , "Learned" , "A herb or a guru" , "Man of wisdom" .)