Unveil suit - the one put on by Stalin? It doesn't do justice to those who've been fitted up! (4,5)
I believe the answer is:
show trial
'it doesn't do justice to those who've been fitted up' is the definition.
The definition suggests a singular noun which matches the answer.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for show trial that I've seen before include "Mock public examination" , "Court proceedings where the guilty decision has been decided in advance" , "legal spectacular" , "This process manipulated" , "Travesty of justice" .)