cut a piece of PVC so your hand fits in it with room to spare , with 2 x 45 degree angles
this is complicated to describe but cut out a square from the top of the pipe wide enough so the handle of the bulldog clip will fit.
Now in the middle of that cut a long notch wide enough for the copper pipe to pass through.
On the other side of the pipe cut a notch out so the pipe from the back of the trigger won’t get trapped.
Then drill 2 holes through and put some cable ties through and attach to the pump so the handle of the bulldog clip is inside the pipe.
Hot glue the pipe to the pump