Bird netting fastened onto your green plastic poles would work if you could get the netting attached to the poles. You might be able to attach the netting to the bottom portion of the lamp fixture itself and let it drape down over the poles.

Another good option is to get green vinyl coated fencing and make a circular shape out of it and attach it around the lamp pole. Depending on the type of clematis you have, it will probably cover the fencing and make it invisible after it matures. If the fencing is not tall enough to reach as high as you require, you could attach one section of the fencing on top of the bottom portion and connect the two sections with cable ties, twist ties, or something similar.

Well, I looked again yesterday, and, never mind. It seems the deer are pulling it down off the supports, and eating it. As of yesterday there was almost nothing left.
Thanks for any suggestions, but it will be useless. I give up. I quit. I can't grow anything they won't eat. And if they don't eat it, they pull it up or break it off and spit it out, then stomp on it, even sticker bushes. If I could shoot them in my neighborhood, I would.
BlueBars

If you really want to grow clematis, then I wouldn't give up. Consider making a double layer of fencing, one inside the other. The inner one would be the used by the clematis to climb on, the outer one would be the one to protect the clematis inside the inner one. There are also products that some have used that repel deer. Either way, trying is half the battle so do consider alternatives before giving up on clematis all together.

My neighbors have grown clematis successfully on their mailboxes. And mine was fine on the lamppost for 2 years. But now it is destroyed and I am defeated. Thanks for the encouragement, but no, I quit. If I attach anything more to the lamppost for the clematis, the deer might pull on that and do damage to the lamppost. No. I quit. I'm done. I have tried every repellent known to mankind to no avail. Lights, squirters, noisemakers, pee of various sorts, hair, bloodmeal, garlic in various forms, soaps of every description. I've even tried netting on my nikko blue hydrangea - they mashed the whole bush to the ground trying to get to the leaves. Trying different things on that for over 6 years, and the only bloom (yes, only one) I got was in the back, against the wall of the house, where you cannot see them. Nice big buds usually form, and before they open they are eaten. I'm going to have to find another hobby, and plant plastic flowers.

Sounds like you need a nice tall fence around your yard!

I want another outside dog! I never had problems when I had a dog. Took me sometime to realize that was the only difference in my area. I just couldn't understand why the deer had started eating my roses and flowers the past few years. Then it hit me...no outside dog! Of course, I live in the country, off the road so the dog can run free. Should work even if fenced in.
Good luck!

The fence, as long as it was high enough, and a dog would be great deer deterrents! Both together would surely do the trick!

Community Association rules - no fence.
County Leash Laws - dogs/cats not allowed to run free.
It would not be fair to a dog to be kept indoors 24x7.
When I move away, it will be to somewhere we are allowed to shoot the deer. Venison's good!
BlueBars