Eyesore you once found on street (4)
I believe the answer is:
stye
'eyesore' is the definition.
(I've seen this before)
'you once found on street' is the wordplay.
'you once' becomes 'ye' (I've seen this in other clues).
'found on' is a charade indicator (letters next to each other).
'street' becomes 'st'.
'ye' put after 'st' is 'STYE'.
(Other definitions for stye that I've seen before include "Red eye" , "swelling by organ" , "Viewer's complaint" , "Inflammation on eyelid" , "Eyelid problem" .)