Filter for first unique instance a column in Excel?

1. Go to the data tab and click on 'Advanced' under 'Sort & Filter';
2. In the pop up, put the list range as the first column (header included) and check the 'Unique records only' checkbox.
3. Click OK and that should be it.

Add an extra column. Use the formula =COUNTIF($A$1:A1,A1) for that column, and copy it to the end

Filter on that column where the value is 1