Nothing to reprove or harangue (5)
I believe the answer is:
orate
'harangue' is the definition.
(I've seen this before)
'nothing to reprove' is the wordplay.
'nothing' becomes 'O' (O resembles 0).
'to reprove' becomes 'rate' (rate could historically mean to reprove or scold).
'o'+'rate'='ORATE'
'or' acts as a link.
(Other definitions for orate that I've seen before include "Harangue" , "Lecture" , "talk at length" , "Give speech" , "Make a formal speech" .)