One's played Shakespearean heroine mostly at home (6)
I believe the answer is:
violin
'one's played' is the definition.
(musical instrument which may be played)
'shakespearean heroine mostly at home' is the wordplay.
'shakespearean heroine' becomes 'viola' (heroine of Shakespeare's Twelfth Night).
'mostly' means to remove the last letter.
'at home' becomes 'in' (similar in meaning).
'viola' with its last letter removed is 'viol'.
'viol'+'in'='VIOLIN'
(Other definitions for violin that I've seen before include "Menuhin's instrument" , "Instrument with four strings" , "A stringed musical instrument, say a Stradivarius" , "It'a played with a bow" , "Bowed instrument" .)