connect the green clip to a grounded part of the boat. Connect it first. Grounded parts could be a negative buss or as mentioned a negative battery post. The purpose of the ground is to discharge any static buildup in the transfer pump. The green connection is not bonding. It is in theory earth ground as opposed to the black conductor which is technically the neutral conductor.
It may be desirable to touch the nozzle tip (if metal) to the metal of the fuel fill fitting to discharge any static buildup in the transfer hose to nozzle plumbing.
Note that if you have shore power and it is connected, your Ground is electrically different than your neutral.