Nothing new in flipping commercial shopping centre (4,3)
I believe the answer is:
damn all
'nothing' is the definition.
('damn all' means absolutely nothing)
'new in flipping commercial shopping centre' is the wordplay.
'new' becomes 'n' (abbreviation as in New Testament NT).
'in' is an insertion indicator.
'flipping' says the letters should be written in reverse.
'commercial' becomes 'ad' (abbreviation for advertisement).
'shopping centre' becomes 'mall' (a mall is a large shopping complex).
'ad' written backwards gives 'da'.
'da'+'mall'='damall'
'n' placed into 'damall' is 'DAMN ALL'.
(Another definition for damn all that I've seen is " Nothing (slang)".)