Swear to be unconcerned about hemp production (9)
I believe the answer is:
blaspheme
'swear' is the definition.
(synonyms)
'unconcerned about hemp production' is the wordplay.
'unconcerned' becomes 'blase' (similar in meaning).
'about' is an insertion indicator.
'production' indicates an anagram.
'hemp' with letters rearranged gives 'phem'.
'blase' placed around 'phem' is 'BLASPHEME'.
'to be' is the link.
(Other definitions for blaspheme that I've seen before include "Speak profanely" , "Utter obscenities or profanities" , "Curse profanely" , "Swear" , "Talk irreverently about God and sacred things" .)