Garment in flat container, poor imitation (8)
I believe the answer is:
travesty
'poor imitation' is the definition.
'garment in flat container' is the wordplay.
'garment' becomes 'vest' (vest is a kind of garment).
'in' is an insertion indicator.
'flat container' becomes 'tray'.
'vest' going inside 'tray' is 'TRAVESTY'.
(Other definitions for travesty that I've seen before include "Absurd misrepresentation" , "Absurd representation" , "Ridiculous version of the genuine article" , "Take off" , "Grossly unfair representation" .)