Clarify, almost cultured (6)
I believe the answer is:
refine
'clarify' is the definition.
(thesaurus)
'almost cultured' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'cultured' becomes 'refined' ('refined' can be a synonym of 'cultured').
'refined' with its last letter removed is 'REFINE'.
(Other definitions for refine that I've seen before include "Purify or improve" , "Cleanse from impurities" , "Remove impurities from (eg, metals)" , "Purify or make more cultured" , "Make pure" .)