Support the new visionary (7)
I believe the answer is:
'visionary' is the definition.
(I know that prophet is a type of diviner)
'support the new' is the wordplay.
'support' becomes 'prop' (prop up can mean to support).
'new' indicates anagramming the letters.
'the' is an anagram of 'het'.
(Other definitions for prophet that I've seen before include "Oracle" , "reader" , "Soothsayer" , "what he says might happen" , "Forecaster (sounding like 4)" .)