Is it possible to clone a Full Sandbox into a Dev Sandbox? I tried using clone but it wouldnt allow me as SF tried to do a like for like clone (full sandbox to full sandbox)
Unfortunately, no. From the documentation:
When you clone a sandbox, all its data and metadata are copied to the new sandbox. A cloned sandbox uses the same license type as its source org. For example, to clone a Full sandbox you must have a Full sandbox license available.