What kind of singer are we talking about here? Famous? It's highly unlikely you would ever get a celebrity to perform.. if it's a singer from your town, ask them.. you should be a little bit more specific
You have to pay them too,most likely someone from your town only.You can contact them and ask them if they can perform.
Well since you probably reffering to a famous singer,
It will be difficult, but not impossible.
Write to them to the angency they record for or call.
And this wont be free either.
Shows they perform are VERY expensive.