Threw up on street. Blimey! (7)
I believe the answer is:
strewth
'blimey' is the definition.
(I've seen this before)
'threw up on street' is the wordplay.
'up' indicates anagramming the letters (letters get chucked up).
'on' means one lot of letters goes inside another (as in clothing \'on\' a person).
'street' becomes 'st' ().
'threw' is an anagram of 'rewth'.
'rewth' enclosing 'st' is 'STREWTH'.
(Other definitions for strewth that I've seen before include "Expression of surprise" , "Aussie exclamation" , "Fancy" , "Said to be amazed" , "Mild expletive" .)