Popular, a New York fixture, whatever happens (2,3,5)
I believe the answer is:
in any event
'whatever happens' is the definition.
(I've seen this before)
'popular a new york fixture' is the wordplay.
'popular' becomes 'in' ('in' can mean trendy).
'new york' becomes 'ny'.
'fixture' becomes 'event' (I've seen this before).
'in'+'a'+'ny'+'event'='IN ANY EVENT'
(Other definitions for in any event that I've seen before include "A versatile athlete may be" , "Anyway" , "Whatever happens" , "How one might describe a decathlete's skill" , "Regardless of circumstances" .)