Trendy positions for cases (9)
I believe the answer is:
instances
'cases' is the definition.
('instance' can be a synonym of 'case')
'trendy positions' is the wordplay.
'trendy' becomes 'in'.
'positions' becomes 'stances' (stance is a kind of position**).
'in'+'stances'='INSTANCES'
'for' acts as a link.
(Other definitions for instances that I've seen before include "Examples, illustrations" , "Incessant (anag)" .)