Grew up - rude about rug before (7)
I believe the answer is:
matured
'grew up' is the definition.
(to grow up is to mature)
'rude about rug before' is the wordplay.
'about' is an anagram indicator.
'rug' becomes 'mat' (both are floor coverings).
'before' is a charade indicator (letters next to each other).
'rude' is an anagram of 'ured'.
'ured' put after 'mat' is 'MATURED'.
(Other definitions for matured that I've seen before include "Ripened" , "Became fully ripe" , "Developed; grew up" , "Mellowed" , "Developed fully" .)