What year is a rare silver dollar?
It is worth whatever melt is. The silver dollar is damaged and they never use rare dates (the 1928 peace dollar is rare, it is likely a 1928-S coin which is quite common) and so it would be worth about $20 for the coin. However, there is the question on whether the money clip itself is silver, usually the clip would be marked "STERLING" or 925 if it is silver. If the clip is silver…
AU means almost uncirculated which is a grade for the coin, depending on the grade on the coin and the year of it, the value of the coin can be from $25 for the most common and lowest grade dollars all the way to $575,000 for the second highest grade, most rare silver dollar(1893S)(no proof 70 silver dollar has ever been found)