Picks claret out after quiet start (7)
I believe the answer is:
plectra
'picks' is the definition.
('plectrum' can be a synonym of 'pick')
'claret out after quiet start' is the wordplay.
'out' is an anagram indicator (out can mean wrong or inaccurate).
'after' means one lot of letters go next to another.
'quiet' becomes 'pp' (music symbol for 'pianissimo').
'start' means to remove the last letter (I've seen 'starts' mean this).
'pp' with its final letter removed is 'p'.
'claret' is an anagram of 'lectra'.
'lectra' put after 'p' is 'PLECTRA'.
(Other definitions for plectra that I've seen before include "Guitar pickers - carp let (anag)" , "Plucky types" , "Guitar picks" , "Bits of plastic maybe" , "Parts for harpsichord" .)