A quiet family member, that's evident (8)
I believe the answer is:
apparent
'that's evident' is the definition.
(synonyms)
'a quiet family member' is the wordplay.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'family member' becomes 'parent' (I've seen this in another clue).
'a'+'p'+'parent'='APPARENT'
(Other definitions for apparent that I've seen before include "Evident, manifest" , "Conspicuous" , "as such an heir" , "Obvious, clearly understood" , "Clearly visible" .)