Streets losing top concert halls (6)
I believe the answer is:
venues
'concert halls' is the definition.
(I've seen this in another clue)
'streets losing top' is the wordplay.
'streets' becomes 'avenues' (avenue is a kind of street).
'losing top' means to remove the first letter.
'avenues' with its initial letter taken away is 'VENUES'.
(Other definitions for venues that I've seen before include "Appointed places for plays or meetings" , "Scenes" .)