Prominent foreigner in 'the Street' (7)
I believe the answer is:
salient
'prominent' 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' going inside 'st' is 'SALIENT'.
(Other definitions for salient that I've seen before include "defence work" , "Prominent, most noticeable" , "Outstanding - it's lean (anag)" , "Entails being most noticeable" , "Noteworthy" .)