To purist rambling is better (8)
I believe the answer is:
outstrip
'is better' is the definition.
(thesaurus)
'to purist rambling' is the wordplay.
'rambling' indicates an anagram.
'to'+'purist'='topurist'
'topurist' with letters rearranged gives 'OUTSTRIP'.
(Other definitions for outstrip that I've seen before include "Go faster or do better than" , "As to purist, surpass or run faster" , "Move faster than and overtake" , "Perform better than" , "Surpass, do better than" .)