Possible Clues:

• Trebly
• How often Daniel Day-Lewis has won Best Actor
• Three times provided by the head of Harrow in an instant
• Once, once more and yet once more
• Number of times 'the brinded cat hath mewed'
• Most of the cereal, as it can be found in little titbits
• 26 as hard in a moment
• '___ the brinded cat hath mewed': Shak
• Cut the grass three times
• Single H, single Y, and isn't that sweet!