Trendy perfume, basically (2,7)
I believe the answer is:
in essence
'basically' is the definition.
('in essence' can be a synonym of 'basically')
'trendy perfume' is the wordplay.
'trendy' becomes 'in'.
'perfume' becomes 'essence' ('essence' can be a synonym of 'perfume').
'in'+'essence'='IN ESSENCE'
(Other definitions for in essence that I've seen before include "Fundamentally" , "Basically" , "at bottom" , "Substantially" .)