Original evidence, trumped up in this case (4)
I believe the answer is:
etui
'this case' is the definition.
(case for needlework equipment)
'original evidence trumped up in' is the wordplay.
'original' indicates taking the first letters.
The first letters of 'evidence trumped up in' is 'ETUI'.
(Other definitions for etui that I've seen before include "Ornamental bag for needles etc." , "Small French case" , "Case containing sharp objects" , "Small needle case e" , "The Case of the Seamstress" .)