after watching video:

too big for 'drip-gully' and ground to 'domed' > but looks fair-to-good for a ditched enclosure - hard to estimate width depth without knowledge of substrate and thickness of soil/suboil

(i guess shallow over broken rocky substrate, so possible matching apparent width well, more likely to be fairly steep sided with some depth, rather than shallow and concave, especially as width looks fairly consistent)

an enclosure could be many possible things, including to enclose round houses etc., but also barrows, ritual spaces, ancient and modern animal pens/shelters and so on ...

BTW Is the photo of the rock carving from the same spot? Reporting rock carvings to Local Groups/County is very useful, as mapping of carvings gets sporadic over large areas. If you can provide grid-ref/map location and photo that would be ideal. Even in areas where programs of mapping carvings are long established, new stuff is found, and old stuff gets lost and found again as vegetation changes. All useful catalogue.

Destruction in peat and moorland fires can reveal quite a lot of new carvings also [:(]