Flimsy Italian buns thrown around street (13)
I believe the answer is:
insubstantial
'flimsy' is the definition.
(thesaurus)
'italian buns thrown around street' is the wordplay.
'thrown' is an anagram indicator.
'around' means one lot of letters goes inside another.
'street' becomes 'st'.
'italian'+'buns'='italianbuns'
'italianbuns' is an anagram of 'insubantial'.
'insubantial' going around 'st' is 'INSUBSTANTIAL'.
(Other definitions for insubstantial that I've seen before include "Flimsy" , "Tenuous" , "Meagre" , "Lacking solidity" .)