Is there an easy way to save a contact for a phone number in the text of an SMS (iphone 4s IOS7) I want to use the number that's in the body of the message, NOT the senders's number.

IOS clearly recognises this as a phone number as it highlights it and gives me the option to dial it, but nothing else. Best I've come up with so far is to dial it, hang up quickly then add the contact from the recent calls list. Is there a graceful solution I'm missing, this sort of thing used to be so easy on an old dumb phone.
Since you're running iOS 7, all you can do is copy it and manually add it to a new contact.

Update to iOS 9.2 and you will get the option to do exactly what you described in your post. Don't worry, even your iPhone 4s should run iOS 9 fine and updating may even make it faster.