AC/DC quiet round piano playing piece (6)
I believe the answer is:
bishop
'playing piece' is the definition.
(chess piece)
'acdc quiet round piano' is the wordplay.
'acdc' becomes 'bi' (AC/DC can informally mean bisexual).
'quiet' becomes 'sh' (both can be said to tell someone to be quiet).
'round' becomes 'o' (round can mean a round object).
'piano' becomes 'p' (musical abbreviation).
'bi'+'sh'+'o'+'p'='BISHOP'
(Other definitions for bishop that I've seen before include "Chess piece and one of the clergy" , "Head of a diocese" , "Chesspiece which moves diagonally" , "Diagonal board mover" , "Senior church minister" .)