No.
NO smart phone for a kid.
If you do, then be ready for all the issues/problems of it.
To me, a kid, even if they pay for it themselves, does not need a smart phone nor one that goes on the internet.
Just get a basic phone.
I work at my kids school, I have a daughter in middle school and I SEE firsthand what the kids do with and on their phones and my daughter also tells me of it. Some kids, have no filters. They have no sense of privacy or keeping to their parent's rules about it, and they HIDE things that they do on it. AND they give away.... their phone number to ANYONE who asks for it (and then that kid gives their phone number to other kids your kid may not even know and on and on) and they even give out their parent's phone number(s) to other kids, they take photos with it, they send it to others and text all sorts of things etc.
So its up to you.
Some kids/families do this: they get their kid/teen a regular basic phone. THEN, if the kid wants to be or is allowed to be nline or do games or text whatever the heck, then they do that AT HOME, only... via the family's computer or iTouch or iPad etc.