Everybody quiet until all Liberal leaders are alike (5)
I believe the answer is:
equal
'alike' is the definition.
(I've seen this before)
'everybody quiet until all liberal leaders' is the wordplay.
'leaders' indicates taking the first letters.
The first letters of 'everybody quiet until all liberal' is 'EQUAL'.
'are' is the link.
(Other definitions for equal that I've seen before include "Commensurate" , "Fifty-fifty" , "Be as good as, match" , "Match, rival" , "On a par" .)