Possible Clues:

• Least
• Set it in maybe, but no more than the minimum
• That's very much like 30 across
• There's very little in one in the examination
• I sent it, being the smallest
• Hardest to see with the naked eye
• Very much by the minute
• Most trifling
• Most wee
• Most insignificant little bird circling European river, endlessly rising