Possible Clues:

• 'You'll love the way we fly' airline
• Split river mouth system
• Rivermouth deposit
• Airline that merged with Northwest in 2008
• Character inside citadel talking
• The fourth Greek letter found at river's mouth
• By the sound of it, gave a hand at the end of the river
• Faucet brand
• Mississippi River feature
• The Greek D (5)