Pressure; emphasis (6)
I believe the answer is:
stress
I believe this clue is a double definition.
'pressure' is the first definition.
(I've seen this before)
'emphasis' is the second definition.
(I know that stress is a type of emphasis)
(Other definitions for stress that I've seen before include "Emphasis: result often of being under pressure" , "Strain or accentuate" , "Highlight" , "Lay emphasis on - it's a strain" , "State mental or emotional strain" .)