Possible Clues:

• It's a mere matter of about fifty to make the bird black
• He sang about Bo and Luke
• With 44-Down, 'Wuthering Heights' actress
• Haggard of country /music
• First name among country crooners
• Country music's Haggard
• Haggard who sang 'Okie From Muskogee'
• To get me around Schubert's king is enough to make the bird black
• European thrush
• Laurence's 'Wuthering Heights' co-star