Incite purist to rebel (4,2)
I believe the answer is:
stir up
'incite' is the definition.
(I know that incite can be written as stir up)
'purist to rebel' is the wordplay.
'to rebel' indicates an anagram.
'purist' is an anagram of 'STIR UP'.
(Other definitions for stir up that I've seen before include "Cause or provoke trouble" , "Instigate" , "Incite; mix" , "Fire in" , "Get excited" .)