Undoubtedly, certainly, of course, as in The coat is expensive, to be sure, but it's bound to last longer than a cheap one. This idiom was first recorded in 1657.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
How to use to be sure in a sentence
I have deserved it to-be-sure, but I do not know how it has happened.Ormond, Volume II (of 3) | Charles Brockden Brown
To-be-sure, no girl ever said she herself, had seen this sight, but she had "heard about it from a last year's girl."
A very common word, to-be-sure, and well understood as to its application.
To-be-sure, the child was a sweet little thing; but they need not make such a rout about it.Arthur Mervyn | Charles Brockden Brown
It was right to assist people in distress, to-be-sure; but to risk his own life he did not think to be his duty.Arthur Mervyn | Charles Brockden Brown