Prophet, character finally appearing in time (4)
I believe the answer is:
ezra
'prophet' is the definition.
(I've seen this before)
'character finally appearing in time' is the wordplay.
'character finally' becomes 'z' (last letter of the alphabet).
'appearing in' means one lot of letters goes inside another.
'time' becomes 'era' (I've seen this before).
'z' placed into 'era' is 'EZRA'.
(Other definitions for ezra that I've seen before include "religious book" , "good book?" , "Book after II Chronicles" , "-- Pound, US poet and critic 1885-1972" , "Old Testament prophet" .)