I think you have slightly mis-understood how to search these maps. You can't put in a term like Clews, which was probably the name of a small farm or hamlet, and expect to pinpoint it. At the most you can put in the name, say, of a small town (like Bellingham), or possibly a village, and then start looking.
Sometimes, when we have found a place on an old map it has taken quite a lot of searching (or squiggling as Boo put it yesterday
)
Look at the census returns; find the place you are interested in, look at neighbouring places, then use that information to locate it on a map. (That is how I found 'Craig' in Corsenside yesterday).
Search the name on the internet, and see if there are any hits that give you a clue as to where it might be.
Often there are no shortcuts. You just have to spend time and scan the map.
As to Clews, I had a look on the Northumberland Communities website,
https://communities.northumberland.gov.uk/ which has a lot of old maps, and found it there.
https://communities.northumberland.gov.uk/007464FS.htm You can see it quite easily, it is just to the north of Bellingham.
Having found it easily on that map I then went to the Old Maps site, and was able to pinpoint it
https://www.old-maps.co.uk/#/Map/384040/585593/12/101338 (you might have to use the - button and zoom out a bit before you can see it)
There is no magic way of find a lot of these places. You sometimes have to be a bit creative in the searching process!
(I think the spot marked with the arrow here on a present-day map
http://www.streetmap.co.uk/map.srf?X=383973&Y=585580&A=Y&Z=115 is approximately where Clews was situated)
