Refurbish diner vet turned upside down (8)
I believe the answer is:
inverted
'turned upside down' is the definition.
('invert' can be a synonym of 'turn upside down')
'refurbish diner vet' is the wordplay.
'refurbish' is an anagram indicator (I've seen 'refurbished' mean this).
'diner'+'vet'='dinervet'
'dinervet' anagrammed gives 'INVERTED'.
(Other definitions for inverted that I've seen before include "Turned upside down" , "Upturned" , "Upside-down" .)