After reading the following passage in chapter 16:-

The whist party soon afterwards breaking up, the players gathered round the other table, and Mr. Collins took his station between his cousin Elizabeth and Mrs. Philips.........(snip)....
"I know very well, madam," said he, "that when persons sit down to a card-table they must take their chance of these things -- and happily I am not in such circumstances as to make five shillings any object. There are undoubtedly many who could not say the same, but thanks to Lady Catherine de Bourgh, I am removed far beyond the necessity of regarding little matters."

*Does that mean that this game is a kind of gambling? And if so, is it ok for the clergyman to do so?

And then we read:-

Mr. Wickham's attention was caught; and after observing Mr. Collins for a few moments, he asked Elizabeth in a low voice whether her relation were very intimately acquainted with the family of de Bourgh.
"Lady Catherine de Bourgh," she replied, "has very lately given him a living. I hardly know how Mr. Collins was first introduced to her notice, but he certainly has not known her long."
"You know of course that Lady Catherine de Bourgh and Lady Anne Darcy were sisters; consequently that she is aunt to the present Mr. Darcy."

** JA tells us at the beginning that Mr. Collins sits between Lizzy and her aunt, that means he is close to her somehow, then Mr. W whisperd to Lizzy (in a low voice, as JA describes ) and ask her about Lady C and so on.