In list<tNode<T>*>::iterator, you have a dependant name, that is, a name that depends on a template parameter.
As such, the compiler can’t inspect list<tNode<T>*> (it doesn’t have its definition at this point) and so it doesn’t know whether list<tNode<T>*>::iterator is either a static field or a type.
In such a situation, the compiler assumes that it is a field, so in your case it yields a syntax error. To solve the issue, just tell the compiler that it is a type by putting a typename ahead of the declaration:
typename list<tNode<T>*>::iterator it