It's used to highlight hemp distributed without additives (8)
I believe the answer is:
emphasis
'it's used to highlight' is the definition.
I can't tell whether this defines the answer.
'hemp distributed without additives' is the wordplay.
'distributed' is an anagram indicator.
'without additives' becomes 'asis' (I can't explain this - if you can you should believe this answer much more).
'hemp' anagrammed gives 'emph'.
'emph'+'asis'='EMPHASIS'
Can you help me to learn more?
(Other definitions for emphasis that I've seen before include "Importance; priority" , "Stress - misshape (anag)" , "Special importance or prominence given to something" , "Stress, accentuation" , "Stress, special importance" .)