Possible Clues:

• Gets down in the air sort of swiftly
• Wide brooks bordering South Downs
• Seasonal flyers
• Birds with forked tails
• Birds roll about on board
• Sound as if my grants come swiftly
• They're fly enough as one takes things as a matter of course
• Believes barrier to be around pigs? On the contrary
• What 4 across does with the birds
• Rules drawn up on troughs for drinks