Looks like Populus simonii to me, though I'd like to see some more close-up pics to be 100% certain. Does the new foliage have a balsam scent?
Hi Michael, here are some others pictures. I didn't notice any special scent on the foliage but it was an old leave. I'll retry with some new foliage.
Still looks OK for Populus simonii, though the location isn't one where I'd expect this - it is a cold-climate species (native to eastern Siberia and NE China) which grows well when planted in N Europe (e.g. Scandinavia), but the heat of Bordeaux would not be good for it. So I still have some doubt that it is that.