How do I format a column in my data set to correctly display time or duration?

I import the data every day from an external Excel spreadsheet, and the format in the Excel sheet is "hh:mm:ss" but when I import it into Analytics it's formatted as "dd mmm yyyy hh:mm:ss".

I'm trying to create a dashboard using telephony data and I need to display the average talk time, but I'm struggling to do that with the whole formatting thing. Any help would be appreciated.