Saying of quiet wanderer, British (7)
I believe the answer is:
proverb
'saying' is the definition.
(proverb is a kind of saying)
'quiet wanderer british' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'wanderer' becomes 'rover' (synonyms).
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'p'+'rover'+'b'='PROVERB'
'of' acts as a link.
(Other definitions for proverb that I've seen before include "Pithy saying expressing a general truth" , "Old saw" , "Aphorism" , "Saying encapsulating a general truth" , "gnome" .)