I have created a saved search in discover, and the field "Clearing" in present in my saved search table.
when adding this field as a control with drop down options the field does now seem to appear even when im using the same index.
Discover generally shows analyzed string fields, while the Options list in a Controls visualization requires a keyword field. The default mapping usually provides both. But you may have custom mapping for your index which may not have both fields.
Things have changed a bit over the major releases. In recent 6.x and 7.x releases you would typically have a field like clearing and another field like clearing.keyword.
In older releases you might have a clearing.raw which is unanalyzed like the keyword.
If you have more questions on this please let us know what version of the stack you are on.
Regards,
Lee