Emphasised fantastic des res on street (8)
I believe the answer is:
stressed
'emphasised' is the definition.
('stress' can be a synonym of 'emphasize')
'fantastic des res on street' is the wordplay.
'fantastic' indicates an anagram.
'on' means one lot of letters goes inside another (as in clothing \'on\' a person).
'street' becomes 'st' ().
'des'+'res'='desres'
'desres' anagrammed gives 'ressed'.
'ressed' placed around 'st' is 'STRESSED'.
(Other definitions for stressed that I've seen before include "anxious" , "Pressurised, strained" , "Physically or mentally overexerted" , "Drew attention to" , "Brought out" .)