Outstanding foreigner in the street (7)
I believe the answer is:
salient
'outstanding' is the definition.
(synonyms)
'foreigner in the street' is the wordplay.
'foreigner' becomes 'alien' (synonyms).
'in the' indicates putting letters inside.
'street' becomes 'st' (abbreviation).
'alien' inserted into 'st' is 'SALIENT'.
(Other definitions for salient that I've seen before include "defence work" , "Noteworthy" , "Leaping (heraldry)" , "Prominent, striking" , "Entails being most noticeable" .)