Possible Clues:

• Plant such as wattle
• Wattle one spies under bill
• Greenish-yellow hue
• Current account - one with a network of branches
• Tree favored by giraffes
• State after repeated account, it's a plant
• A blooming double century with a single A
• Tannin source
• First class accountants head over heels about the plant
• Bill joins a security organisation - it has a number of branches