keyword not provided??

I have a site that I am currently building for my mates local business. I have all the keywords I'm targeting in market samurai and am tracking it's progress weekly. I'm checking the statistics of the site i.e traffic andsource threw google anylatics, over the last few days it has been getting a regular supply of traffic from a search query but it doesn't state the query. Any ideas how to find this out?

Google anylatics shows all the querys the site is fount for except 1. All it displays is (not provided) It's annoying as it is generating a fair bit of traffic.

Cheers for that thejake but I think I'll skip paying Google $150 and stay in the dark. It's bringing me traffic so can't moan