Emphasis on pronunciation (6)
I believe the answer is:
accent
I believe this clue is a double definition.
'emphasis' is the first definition.
(synonyms)
'pronunciation' is the second definition.
(accent is a kind of pronunciation)
'on' acts as a link.
(Other definitions for accent that I've seen before include "Emphasis; mark on a letter" , "Distinctive local way of speaking" , "Mark to modify letter" , "Distinctive manner of oral expression" , "Distinctive way of talking" .)