Notice communist get mad (3,3)
I believe the answer is:
see red
'get mad' is the definition.
(I've seen this in another clue)
'notice communist' is the wordplay.
'notice' becomes 'see' (notice can mean to spot or see).
'communist' becomes 'red' (red can informally mean communist).
'see'+'red'='SEE RED'
(Other definitions for see red that I've seen before include "Burst a blood vessel" , "Become furious" , "Lose temper as bull might" , "Lose temper like angry bull" , "Be suddenly angry, as bull might" .)