Related Clues:

• Underground part of plant
• Cause or motive
• Sanity, the ability to think
• Underground part of a plant
• Sanity and logic
• Logic and rationality
• Cause for sanity
• Ability to think rationally
• 'Motivation, grounds (6)'
• Motive for an action
• Why, that's about a child!
• Is this why one might think about a start for 33 across?
• Having no feet they can only totter, it seems
• Is this why it's about one of the next generation?
• There's some sense about a boy of yours