Evens it'll get a radical preacher on box (13)
I believe the answer is:
televangelist
'preacher on box' is the definition.
'evens it'll get a radical' is the wordplay.
'radical' is an anagram indicator.
'evens'+'itll'+'get'+'a'='evensitllgeta'
'evensitllgeta' anagrammed gives 'TELEVANGELIST'.
(Other definitions for televangelist that I've seen before include "TV preacher" , "Revivalist who broadcasts" .)