I think this place name is written "Old Duda", however I am confident it is referring to a place called "Old Wooda" in Tavistock parish. If spoken out loud there is a very minimal audible difference between the two spellings even though they look completely different. The spelling Duda is just a mistake.
Old Wooda was the name of a small group of dwellings on the outskirts of Tavistock.
This place is shown on a later 1884 map:
The reason I am confident this is the correct place is because looking at the original 1841 census page, the places enumerated immediately before were Indescomb Farm and Cottage, and two pages earlier Tavy Cottage. Looking at the map above, it appears the path the enumerator took was down Exeter Street towards the town.
It can also be useful to review the Enumeration District Description on the first page of each 1841 census book, to get an idea of the path the enumerator took through the district. On Ancestry.co.uk, you can view this by scrolling back to the first page in a given folio series. It is not particularly helpful in this case as I am not very familiar with the local geography, but I will include it here for completeness (perhaps you can examine the maps more carefully to work out the exact route the enumerator took, and where all the mentioned landmarks were located):
Finally, checking the 1851 census confirms that this place is Old Wooda. The Snell family are still living at Indiscombe, and enumerated immediately after them are several families at "Old Wood". One of these families is a Williams family – perhaps related to the Ann Williams living there in 1841. To view the page in full, the census reference for this place in 1851 is HO 107/1883, f 369, p 16:
The fact that there were several more families living at Old Wooda in 1851 compared to 1841 suggests there may have been some building and expansion there between the censuses.