Emphasise tension (6)
I believe the answer is:
stress
I believe this is a double definition.
'emphasise' is the first definition.
(synonyms)
'tension' is the second definition.
(synonyms)
(Other definitions for stress that I've seen before include "Force" , "Emotional tension" , "'Strain, tension (6)'" , "Tension, pressure" , "possible excuse for sickie?" .)