Possible Clues:

• Figure of speech like 'no mean feat'
• It's no small matter, perhaps, editing T. S. Eliot
• One rather young to be embroiled in romances? That's an understatement
• Tells tales about infant? That could be an understatement
• Little child in stories making understatement
• Rhetorical device in stories enthralling small child
• Child tucking into pork pies not the smallest, for example
• Kid in stories not exactly well-behaved, for example
• Untidy toilets? That's some understatement!
• It downplays setter getting eaten by 50 bears