Registry Line Export/Import

Hi , i deleted a registry line from my win7 registry as a leftover from an unistalled app and i want to re-import it as it causes problems. I have a backup or the whole registry but i have installed a couple of programs since then with installers that probably have altered the registry. So importing this older backup is not a good idea right?

Can i export this certain line alone (from the backup file) and then import it in my current registry?

thanks