Ordinary charge to speak (5)
I believe the answer is:
orate
'speak' is the definition.
(I know this)
'ordinary charge' is the wordplay.
'ordinary' becomes 'O' (abbreviation e.g. O-Levels).
'charge' becomes 'rate' (rate is a kind of charge).
'o'+'rate'='ORATE'
'to' is the link.
(Other definitions for orate that I've seen before include "Speaker may" , "Talk pompously" , "Deliver a speech" , "Speechify" , "Make a formal address" .)