The fact is, the Time Traveller was one of those men who are too clever to be believed: you never felt that you saw all round him; you always suspected some subtle reserve, some ingenuity in ambush, behind his lucid frankness.
There are no more uses of "ingenuity" in the book.
Show samples from other sources
He exercised great ingenuity in making excuses for missing class.
It will take more than ingenuity to clean this up. We’re going to have to admit our mistake.