Possible Clues:

• Australian tree
• Yellow-flowering shrub
• Top-rate accountants set up plant
• Plant an accountant in a federal US bureau
• Plant spies on an accountant
• After a century, a tree comes to a finish of intelligence
• Twice a century it starts to grow into a tree
• How an accountant may get planted on american intelligence
• Tree from which giraffes browse
• Tree or shrub with yellow or white flowers