How liars start to think about travesty of justice (4,5)
I believe the answer is:
show trial
'travesty of justice' is the definition.
(I've seen this before)
'how liars start to think about' is the wordplay.
'start to' indicates taking the first letters.
'about' indicates an anagram.
The initial letter of 'think' is 't'.
'how'+'liars'+'t'='howliarst'
'howliarst' with letters rearranged gives 'SHOW TRIAL'.
(Other definitions for show trial that I've seen before include "legal spectacular" , "This process manipulated" , "Travesty of justice" , "Mock public examination" , "Court proceedings where the guilty decision has been decided in advance" .)