Possible Clues:

• It can cause one to turn blue
• One for this if it's in black and white
• Regret alternative runs during broadcast
• Sadness,regret
• Shakespeare : 'Parting is such sweet . . . . . .'
• ` `Parting is such sweet ......' '
• One for this, and there you have it in black and white in the air
• Shakespeare 'Parting is such sweet . . . . . .''
• That's 27 across with one magpie
• Is that what a magpie is for?