I don't know what this is. Eileen will probably know. She'll tell you. I grow a few weeds in my garden on purpose because I really like them and maybe they were miss-classed as weeds. I have butterfly weed, Common Milkweed and Joe Pye Weed. They are all weeds, but beautiful to me so they stay.

I am looking at this on a very small screen, so a few questions if you don't mind. {sorry about this ;o)}

is that a flower bud at the top? is it a climber or is it multi stemmed and are the lower leaves notched [the ones next to your fingers] or nibbled by pests?
is it only one or several of them? is it in the edge of the hedge or in open soil?

Looks like a light-starved clematis to me, there are some with notably serrated leaves. Is there something that looks similar on the other side of a nearby fence?

It looks like the leaves have been attacked by something, perhaps vine weevil but I would guess that it is a Pittosporum seedling.

the stem that seems to be going off side-wards to the left looks like honeysuckle. the other stem as if it has been nibbled.
to answer your original question is it a weed or a plant the answer is yes its a plant but only a weed if it is in the wrong place or you don't want it.

why not pot it up and see what it becomes. if you like it replant if not compost it.

I’m a bit late seeing this but, like Sbg, I think it is honeysuckle. I get a lot of this in my garden. I tend to leave it if it’s in a suitable place, but it is rampant and can become a bit of a thug - I find the longer it is left, the more difficult it is to remove.

Thanks everyone, I’ve put it in a pot and see how it goes on from there 😀