You already have an answer to this question that I believe is correct. I don't think I'll tell you anything you don't already know but I'll wax on a bit more about my usual sub-conscious process for deciphering a difficult word.
What does it look like it says?
I would likely transcribe this birthplace as "Vender". Depending on the consistency of the writer, it can sometimes be useful to compare individual letters, and in this case the "e" and "n" in particular are quite consistent with other examples of those letters given in the excerpt. The last letter may be an "e" or an "r", it is difficult to say. However, I would caution against over-interpreting individual letters. Writers sometimes scribble or omit letters but it may not be a misspelling as such. Remember people aren't typewriters.
Does this transcription make sense?
Google is your friend. Searching for
vender, france doesn't produce many promising results for a place in France. But Google does make a useful suggestion:
So we have a possible answer, now: Vendée, a department in France.
Why might the place have been spelled like this?
Think about the record itself. How was the information collected? Who was writing it down?
In this case, it is a census record from 1881. The form you are looking at is the form the enumerator copied all the information to, but the original data would have been household schedules (like those that survive for the 1911 census). This means that the householder would have filled out the schedule, and then the enumerator came along and collected the schedules. It was then the enumerator's job to transfer all the information on the schedules to the census forms we can view today. In cases where the householder was illiterate, a neighbor or the enumerator himself may have filled in the schedule for them.
This tells us a couple of things. The spelling could simply be due to an error in the enumerator transferring over the information from the schedule to the census form. We do not know who filled out the household schedule (Pierre, a neighbor, the enumerator), but the spelling could equally have just been a phonetic interpretation of Vendée.
Does looking at other entries help?
As suggested by @PolyGeo in the comments, it can sometimes be useful to look at adjacent entries or pages. We might get a better idea of the way the enumerator recorded foreign countries.
In this case, I don't think this is particularly helpful, probably for the reasons noted above - the enumerator simply transferred the information from the household schedule over to the census forms, and may not have attempted to make all place names consistent. For example, you'll note that a few lines below Pierre is a person born in "Alsatz Lorraine", so it appears the enumerator was not very consistent in the format of recording foreign birthplaces.
What do the instructions say?
When looking at a census, it's sometimes useful to look at the instructions. But keep in mind that people are terrible at following instructions.
Looking at the 1881 census household schedule, the column heading for "Where Born" says:
If the instructions had been followed, the entry would just say "France" - so consider yourself lucky that they didn't follow the instructions perfectly.
What to conclude?
I know that this probably the only record you currently have that narrows down where Pierre was born in France. But I would again be cautious against over-interpretting the record. Remember this is just one instance where he stated his birthplace, and he could have been wrong. He could have just been remembering a place he spent time in early childhood.
By all means, pursue birth records in Vendée, as this seems the most likely birthplace, but don't get discouraged if nothing turns up. This is still quite a large area to search. In cases like this it is important to think about what other types of records may hint at his place of origin in France - and your other question addresses this.