Purify, process (6)
I believe the answer is:
refine
This clue is a double definition.
'purify' is the first definition.
(I know that refine is a more specific form of the action purify)
'process' is the second definition.
(I know that refine is a more specific form of the action process)
(Other definitions for refine that I've seen before include "Make pure" , "Remove impurities as from oil" , "Make purer" , "Purify or improve" , "Filter or process as with oil" .)