JBL Clip 3 won’t pair with iPod

Have you put the Clip 3 into discovery mode? If it's like the Charge 3, the Clip 3 will have a Bluetooth button that you press to put it into discovery mode. You only have about thirty seconds to pair with it before the discovery mode is turned off.

If that doesn't sort it out, try the following suggestions as a last resort:

1. turn off the Bluetooth on any other devices nearby. Either turn them off or move out of range of them. This suggestion is based on preventing any other Bluetooth devices from interfering with the pairing process
2. see if you can tell your iPod to forget that Bluetooth device, then search for it again. I think that if you long tap on the device in your iPod's menu, it may bring up an option to forget it. The idea here is that if the information your iPod sees is corrupted, then by forgetting the device and then trying again from scratch, it might work (no guarantees unfortunately)
3. Your iPod is quite an old model, so there's an outside chance that its Bluetooth is not compatible with the Clip 3, even though it works with the Charge 3.