I don't know any way. You can declare alias with a using-directive.

 

using MyQuery = System.Linq.Expressions.Expression<System.Func<System.Linq.IQueryable<int>, System.Linq.IQueryable<int>>>;

 

However it doesn't work to declare a 'generic' alias Sad :

// Does NOT work =( 
  
using MyQuery<T> = System.Linq.Expressions.Expression<System.Func<System.Linq.IQueryable<T>, System.Linq.IQueryable<T>>>;