Object knocked over in elegant cafe (trattoria) (8)
I believe the answer is:
artefact
'object' is the definition.
(artefact is a kind of object)
'knocked over in elegant cafe trattoria' is the wordplay.
'knocked over' is a reversal indicator.
'in' says the answer is hidden in the clue.
'tcafetra' is hidden within 'elegant cafe trattoria'.
'tcafetra' back-to-front is 'ARTEFACT'.
(Other definitions for artefact that I've seen before include "Something created" , "Human-made article" , "Article of human workmanship" , "Item made by human" , "Thing made by human workmanship" .)