Applaud first communist revolution (4)
I believe the answer is:
clap
'applaud' is the definition.
(synonyms)
'first communist revolution' is the wordplay.
'first communist' becomes 'c' (1st letter of 'communist').
'revolution' becomes 'lap' (I've seen this before).
'c'+'lap'='CLAP'
(Other definitions for clap that I've seen before include "Make sound of applause" , "Applaud manually" , "Applaud in manual way" , "Pat" , "express approval" .)