Point duet out as a piece of music (5)
I believe the answer is:
etude
'a piece of music' is the definition.
(I know this)
'point duet out' is the wordplay.
'point' becomes 'e' (compass point).
'out' indicates an anagram (out can mean wrong or inaccurate).
'duet' is an anagram of 'tude'.
'e'+'tude'='ETUDE'
'as' is the link.
(Other definitions for etude that I've seen before include "(Musical) study" , "Indian statesman" , "A short musical exercise" , "bit of practice" , "Noted composition" .)