Italicize, say (6)
I believe the answer is:
stress
This clue is a double definition.
'italicize' is the first definition.
(I've seen this in another clue)
'say' is the second definition.
(I know that stress is a more specific form of say)
(Other definitions for stress that I've seen before include "Dwell on" , "Highlight" , "suffering" , "Emphasise the strain" , "Emphasise the pressure" .)